I recently got back from a vacation in Thailand and have been experimenting at home with some of the things I ate on my trip. Although I have yet to succed at making an edible curry paste from scratch (each attempt has been a spectacular disaster), I thought a premade curry paste would be a nice spicy complement to a sweeter vegetable dish with a salty feta topping. The framework for the recipe came from Cooks Illustrated's Scalloped Potatoes with Root Vegetables. —VanessaS
Slice the sweet potato and parnsip into 1/8 inch thick slices on a mandolin. Set aside.
In a large dutch oven with a lot of surface area, melt the butter over medium heat. Add the onion, garlic, ginger and a pinch of salt to the pot and saute until translucent, stirring occasionally. Add the curry paste and stir until combined and no clumps remain.
Add the parsnips, cream, and stock to the pot and bring to a simmer. Cover the pot and let simmer for 5 minutes. Add the sweet potato to the pot and bring it back to a simmer. Cover and let simmer about 10 minutes, until the sweet potatoes are just tender enough to pierce with a knife.
Pour the contents of the pot into an 8 inch by 8 inch baking dish and sprinkle the top with feta. Bake for about 17 to 20 minutes, until the feta is browned and the cream bubbles.