Roll out the pastry crust on a lightly floured surface to an 11-inch round, about 1/8 inch thick. Fit it into a tart pan with a removable bottom, pressing into the edges and trimming excess dough. Chill for 30 minutes.

Preheat the oven to 375°F.

Line the chilled crust with parchment paper and fill with pie weights. Bake on a sheet until edges are golden, about 15 minutes.

Remove weights and parchment, and bake crust for another 15 minutes until set. Let it cool.

Melt butter in a pan, add onions, season with salt, and cook until soft and water has evaporated.

In a separate skillet, cook bacon until crisp. Combine with onions, season with pepper, and spread in the tart shell. Top with Gruyère cheese.

Whisk together eggs and cream, pour over the tart filling, and sprinkle with thyme.

Bake the quiche until set, about 30 minutes. Let it cool for 30 minutes before serving.

DEVOUR!