This quiche-like tart comes from Helvetia, West Virginia, and was inspired by the Swiss heritage of the town’s settlers. The caramelization of the onions perfectly matches the buttery, flaky crust.
For the Pastry
- 2 1⁄2 cups all-purpose flour
- 1⁄2 tsp. baking powder
- 1⁄2 tsp. salt
- 1⁄2 cup Crisco
- 1 1⁄2 cups milk
For the Filling
- 1 stick unsalted butter, plus more for the top of tart
- 2 1⁄2 – 3 lb. onions, thinly sliced
- 9 eggs
- 2 cups milk
- 2 tsp. salt
- Freshly grated nutmeg
- For the pastry: Combine flour, baking powder, and salt in a medium bowl. Using a pastry cutter or two knives, cut in Crisco until mixture resembles a coarse meal. Stir in milk with a fork until dough forms. Knead 3 times. Gather into a ball, wrap in plastic, and chill at least 1 hour.
- Preheat oven to 375°. On a floured surface, roll out dough into a large rectangle. Press into a 9″ × 13″ baking pan and prick with a fork. Bake 10 minutes.
- For the filling: In a large skillet, melt 1 stick butter over medium-low heat. Add onions; cook, covered, until tender but not brown, about 25 minutes. Remove from heat, cool slightly, and place in crust.
- Preheat oven to 450°. In a medium bowl, beat eggs with milk and salt. Pour slowly over onions. Sprinkle with nutmeg and dot with butter. Brown 10 minutes. Reduce heat to 350° and bake until custard is set, about 30 minutes.