Adapted from the Flour Sack, this recipe uses teff flour for the crust which has a wonderfully earthy flavor that pairs nicely with the sweet potato filling. Feel free to swap in different cheeses or any winter-y vegetables that you have on hand, as long as the flavor profiles match. —Posie (Harwood) Brien
Grease a 10-inch deep-dish tart pan with a removable bottom or a springform pan.
Mix all of the crust ingredients together. Pour the dough in the pan and press it down, starting in the middle, to form a crust of even thickness with 1-inch or 1 1/2-inch sides. Prick the crust all over with a fork. Cover it with plastic and refrigerate it for 1 hour or overnight.
Preheat the oven to 375 degrees. Put pie weights or dried beans upon parchment in the crust. Bake the crust for 10 to 12 minutes until it begins to pull away from the edges. Remove the weights and bake it for another 3 or 4 minutes just until the crust is dry. Let the crust cool before adding the filling.
For the filling: Mix the sweet potatoes with enough olive oil to coat them as well a pinch of salt. Roast them in the oven until a fork can pierce them easily--about 15 minutes. Let them cool.
Meanwhile, heat 2 tablespoons of olive oil in a large frying pan. Add the onion and cook them over medium-low heat, stirring often, until they caramelize (this takes awhile! About 35 minutes. Persevere…it is worth it.) Add the balsamic vinegar and continue to cook them until the liquid has evaporated. Transfer them to a bowl.
Add some olive oil to a frying pan and cook the garlic over medium-low heat until it begins smell heavenly. Add the Swiss chard stems and cook them for a few minutes. Add the rest of the chard and cook until the leaves are wilted. Turn the heat off and add the onions, sweet potatoes, 1/3 of the cheese, a 1/4 teaspoon of red pepper flakes, and some freshly ground pepper. Whisk the eggs in a bowl and then add them to the mixture, stirring to combine.
Pour the filling into the crust and then crumble the remaining cheese on top. Bake for 35-40 minutes at 375 degrees.