This pie has a vibrant purple layer made from Okinawan sweet potatoes which are naturally purple, a rich coconut milk layer that has the consistency of firm gelatin though it’s made from only sugar, cornstarch, water, and coconut milk, and a delicate shortbread pie crust. Since the Okinawan sweet potatoes taste similar to chestnuts or taro, it is reminiscent in flavor (but not texture) to a Chinese-style sponge cake filled with a chestnut purée. It can be made any time of the year; it would be fun to serve as an unusual Hawaiian-inspired alternative to the traditional Thanksgiving sweet potato pie.
Okinawan sweet potatoes have tan or brown skin and a dark purple flesh that becomes even more vibrant when cooked. They have a dry dense texture, taste sweet, and their flavor is similar to chestnuts or taro. They are most likely to be found in Hawaiian or Japanese grocery stores. This pie must be made with Okinawan sweet potatoes; other types of yam or sweet potatoes cannot be substituted because their flavor and texture is very different.
Source: Modified from “Okinawan Sweet Potato Pie with Haupia Topping” reprinted in “Best of the Best from Hawaii Cookbook: Selected Recipes from Hawaii’s Favorite Cookbooks” edited by Gwen McKee and Barbara Moseley. The recipe is originally from “Hawai’i’s Best Local Desserts”.
(Hawaiian) Okinawan Sweet Potato Pie with Haupia Topping
Ingredients
Press-In Shortbread Crust:
- 2 Tbsp sugar
- 1-1/2 cups flour
- 1-1/2 sticks cold butter (12 Tbsp, 3/4 cup)
- (optional) 1/2 cups chopped toasted Macadamia nuts
Okinawan Sweet Potato Filling:
- 1 stick room temperature butter (8 Tbsp, 1/2 cup)
- 3/4 cup sugar
- 2 eggs, beaten
- 2 generous cups Okinawan sweet potato
- 1/2 cup evaporated milk
- 1 tsp vanilla
- 1/4 tsp salt
Haupia Topping (Coconut Pudding):
- 5-1/2 Tbsp sugar
- 2/5 cup cornstarch (about 6-1/2 Tbsp)
- 1-1/8 cup water (1 cup + 2 Tbsp)
- 1 can (19 oz) coconut milk (preferably Mae Ploy brand since it is very creamy)
- 1/4 tsp salt
Press-In Shortbread Crust:
Preheat the oven to 325 F. Butter or lightly oil a pie pan or a rectangular-shaped or square-shaped baking pan if you would like to make bars. Combine the sugar and flour. Cut or use your fingers to rub the butter into the flour mixture until sandy. If the butter starts to melt or becomes too soft, place it in the refrigerator or freezer for a few minutes to cool and then continue.
Press the crust mixture lightly into the bottom baking pan as evenly as possible. If you are using a pie pan, then press the crust mixer lightly onto the sides of the pan and use a table knife to cut the top of the crust to an even length. If you are using a rectangular or square-shaped baking pan, there is no need to press the crust mixture onto the sides (The Okinawan sweet potato filling which touches the sides of the baking pan may turn brown after baking; if so you can trim off a thin slice of the brown edges before cutting the pie into squares or bars). Freeze the crust for at least 30 minutes to firm it before baking. The unbaked crust can be made ahead of time and stored frozen.
Bake at 325 F for 20 – 25 minutes, or until the crust is pale but very lightly browned. Let cool.
Okinawan Sweet Potato Filling:
Preheat the oven to 350 F.
You can cook the Okinawan sweet potatoes by baking, boiling, or steaming them. I suggest steaming them whole, since this best preserves their color and moisture.
To steam the Okinawan sweet potatoes whole: Fill the bottom of a large pot with a tight-fitting lid with a few inches of water (the water level should be below the shelf of your steaming rack or metal colander so that the Okinawan sweet potatoes don’t get wet). Heat on high until boiling. Reduce heat to medium. Place a metal steaming rack or metal colander in the pot. Place the Okinawan sweet potatoes on the rack, cover with a tight-fitting lid, and steam until they can easily be pierced with a fork (about 30 minutes). They should be steamed over gentle heat; reduce the heat if the top of the pot is clanking a lot due to releasing steam.
When the Okinawan sweet potatoes are cool enough to handle, peel them and then mash them. I suggest using a potato ricer to get the finest consistency so that the pie has a smooth texture.
Beat the butter and sugar. Mix in the eggs. Gradually mix in 2 cups of mashed Okinawan sweet potatoes. Add the evaporated milk, vanilla, and salt. Slowly increase the mixing level to medium-high and whip the mixture as you would to make whipped potatoes (e.g. to level 8 out of 10) in order to incorporate air into the filling.
Pour the filling into the crust; stop when it fills the crust halfway. If you have extra filling, you can bake it in another pan to make a crust-less pie or you can make an additional crust to bake it in (the pie tastes best with the shortbread crust).
Cover the edges of the pie with aluminum foil so that the edges won’t become overly browned. Bake at 350 F for 30 to 35 minutes, or until a toothpick comes out mostly clean but has a few moist crumbs stuck to it or some moisture on it (this indicates that the filling is cooked through but is still moist). Cool.
Haupia Topping (Coconut Pudding):
Mix sugar, salt, and cornstarch in a medium pot. Stir in water and blend well. Add the coconut milk. Cook over medium-low heat, stirring constantly, until the mixture thickens, but doesn’t boil. It will become very thick, similar to a frosting.
Cool slightly, and then pour the haupia over the pie filling, until it covers the pie and nearly fills the crust if you are using a pie pan (a small portion of the sides of the crust should peek out above the haupia). Use a spatula to smooth the top of the haupia topping.
If you have extra haupia then it can be spread over the extra baked Okinawan sweet potatoes filling if you made some or the extra haupia can be spread in a new pan and served as a separate dessert after it has solidified (cut into bars before serving).
Refrigerate; the haupia will become solid, similar in texture to Jello and other gelatin desserts.
Lox, Stock, and Barrel 
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Great post on Hawaii. I would like to visit Hawaii — I will make sure to check out the farmer’s markets!
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Thanks for posting this recipe! I stopped at an Asian grocery while I was traveling and found the sweet potatoes, so I was able to make this pie. My bars were not real pretty (I’m not good at creating level layers), but they were tasty, and sooo rich!
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Nice! I’m glad you liked the recipe and that it turned out well. 🙂
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AMAZING! I’ve made this pie a few times and everyone I share it with loves it! Very unique and popular at gatherings 🙂
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I love this pie too. I’m so glad that you and everyone else you’ve made it for likes the recipe. Thanks for letting me know!
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Hi! I love your blog and this recipe sounds fantastic. I was wondering if the macadamia nuts should be toasted before adding it into the crust or not toasted at all, thank you!
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Oh goodness I didn’t see that you wrote “toasted” in the ingredient list, please disregard my previous question.
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Hi Tiffany,
No problem. I’m happy to answer questions any time you have them.
-Jenny
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Ah I actually do have another question, Jenny. I was unable to find the okinawan sweet potato after visiting 3 grocery markets and one of them was a Japanese market. Would using a purple sweet potato with a dark gray/purple skin be a good substitute? If so, have you ever made the pie with them before? Thank you so much for taking the time to answer the! (:
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Okinawan potatoes have purple flesh, and they have a very particular taste that other sweet potatoes don’t have — they taste like chestnuts. Switching sweet potato types will change the flavor and color. Okinawan potatoes are dry like regular potatoes; some sweet potatoes are moister, so substituting them may change the texture or may require the pie to be baked for longer.
I’ve not tried other types of sweet potatoes in this recipe, so I don’t know how it will come out. But I think it would be an interesting experiment. If you try another type of sweet potato, I suggest tasting the batter as you mix it and if necessary adjusting it. For example, your sweet potatoes may differ in sweetness, so you might want to increase or decrease the evaporated milk or sugar. There are several tasty desserts made with regular sweet potatoes, so it’s possible that a different potato type might be good in its own way, even though it will be very different than the pie in the recipe.
If you try it, let me know how it turns out!
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Hi, Thank you for posting this recipe! I moved off-island a year ago…I miss this so much, I’m even going to order Okinawan sweet potatoes online since they are not available in grocery stores where I live. Just a question — about how many sweet potatoes (preferably in lbs) yield two cups mashed?
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I don’t have the exact conversion from pounds of Okinawan sweet potatoes to cups mashed right now (though you’re right that I should measure this). However, generally 1 lbs of regular white potatoes makes 1-3/4 cups mashed potatoes; I think you can use this to estimate how many pounds you need (order some extra potatoes just in case).
Let me know how many cups of mashed potatoes that your lbs makes!
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This recipe was so good. Thank you for sharing.
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You’re welcome!
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Thank you for posting this recipe!!! My husband is really into the Okinawan sweet potatoes, so I tried an Okinawan sweet potato pie with a butter crust. It was good but I came across your recipe and thought I would try it (sans haupia topping – a dollop of whip cream instead) for Thanksgiving dessert. My husband’s one word, “BRILLIANT!”
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I have been using your recipes for years! I love it and so as my husband who is from Okinawa! Thank you for this amazing recipe!
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