This is a GAME-CHANGER!!
1 lb. sweet potatoes
10 oz. baby penne or other short, small pasta (approx. 2 cups)
4 tbs. butter, softened
3 tbs. all-purpose flour
2 cups whole milk
1 tsp. English mustard
1/4 tsp. paprika, plus 1/4 tsp. to sprinkle on top
3/4 cup crumbled feta cheese
1 1/4 cups grated sharp Cheddar cheese, plus 1/4 cup to sprinkle on top
4 fresh sage leaves
salt and pepper to taste
Heat the oven to 400°F. Put a large saucepan of water on to boil. (A lid makes this go faster.)
Peel the sweet potatoes and cut into rough 1″ pieces. When the water is boiling, add salt to taste and cook the sweet potatoes for about 10 minutes, or until they are soft. Scoop them out with a spider or slotted spoon, then mash them roughly. Do not throw out the water.
In another saucepan, gently melt the butter, then whisk in the flour to make a roux. Take the pan off the heat and slowly add the milk until everything is combined and smooth. Change to a wooden spoon and continue to stir until the flour taste has cooked away and the sauce is thickened, 3-4 minutes. Stir in the mustard, 1/4 tsp. of paprika and a bit of seasoning.
Cook the pasta in the reserved water according to package directions until just al dente. Reserve some of the cooking water, then drain and stir into the sweet potatoes. Stir in the feta cheese, then stir in the sauce and the 1 1/4 cups Cheddar cheese. Add some of the reserved cooking water if it seems too thick. Check seasoning again.
Spoon into 4 small overproof dishes (1 1/2-1 3/4″) or 1 baking dish (12×8″). Sprinkle with the remaining Cheddar cheese and paprika, then shred the sage leaves and scatter over.
Place on a baking sheet and bake for 30-35 minutes, until the top is bubbly and everything is piping hot.