Alsace Onion Tart (Tarte à l’Oignon)

Instructions

1. 1

   Preheat oven to 375°F (190°C). Roll out pie crust and press into a 9-inch tart pan. Trim edges and prick bottom with a fork. Line with parchment paper and fill with pie weights. Blind bake for 12 minutes, then remove weights and parchment and bake 5 more minutes until lightly golden.

2. 2

   In a large skillet, melt butter over medium-low heat. Add sliced onions and cook slowly, stirring occasionally, for 25-30 minutes until deeply golden and caramelized. If using bacon, add it during the last 5 minutes of cooking. Season with a pinch of salt and set aside to cool slightly.
3. 3

   In a mixing bowl, whisk together eggs, heavy cream, salt, pepper, and nutmeg until well combined and smooth. This creates the creamy custard base that will bind everything together.

4. 4

   Spread the caramelized onions evenly in the pre-baked tart shell. Pour the custard mixture over the onions, ensuring it distributes evenly throughout.

5. 5

   Reduce oven temperature to 350°F (175°C). Bake the tart for 30-35 minutes until the custard is set and lightly golden on top. A knife inserted in the center should come out clean. Cool for 10 minutes before slicing.