For the CRUST:
3/4 c cold, unsalted butter (1 1/2 sticks)
2 Tbsp sugar
1 3/4 c flour
1 c macadamia nuts, well chopped
Mix the dry ingredients together, then add nuts and butter, cutting with a pastry cutter until crumbly, then press into pie pan. Or you can use a premade crust, which is what I did.
For the OKINAWAN SWEET POTATO layer:
1/2 c butter, softened
1 c sugar
2 eggs, beaten
2 c okinawan sweet potatoes, peeled, boiled and mashed (about 1 big potato)
1/2 c evaporated milk
1 tsp vanilla extract
1/4 tsp salt
Cream butter and sugar until smooth in medium bowl. Add eggs, then mashed potato, then the remaining ingredients. Spread into the crust but leave a half inch for the haupia on top. Bake the pie at 350F for 30 minutes (mine took 40 minutes) until the crust is golden and the potato filling is lightly browning. Let cool.
For the HAUPIA LAYER: (do not start until the potato filling is cool)
1 can coconut milk (13.5 oz.)
1/2 c water
1/3 c sugar
1/3 c cornstarch
Put the milk and water into pan. Mix sugar and cornstarch together, then add to the liquids. Turn on medium heat and stir constantly until dissoved and thickened, several minutes. Quickly pour haupia over pie evenly and refrigerate for a few hours or overnight. Cut and serve when cooled.
I know, it seems like a lot of work. But trust me, it's TOTALLY worth it. The light sweet potato flavor combines extremely well with the sweet coconut topping. Plus, it's so pretty!
Edited to include a pic of this pie which I made for 10-31-11. These potatoes were perfectly ripe and fresh, and when I steamed them they turned a beautiful vibrant dark purple. I had to make a pie.