On a lightly floured work surface, roll dough into a 16-inch round. With a dry pastry brush, sweep off any excess flour; fit dough into a 2-inch deep-dish tart pan with a removable bottom, gently pressing it into the sides. Using a sharp knife, trim the dough evenly with the edge of the pan. Cover with plastic wrap; chill tart shell until firm, about 20 minutes.

Preheat oven to 375 degrees.

Line the tart dough with a sheet of parchment paper and fill with pie weights. Transfer to oven and bake until light brown, about 25 minutes. Remove weights and parchment paper and continue baking until golden brown, about 5 minutes. Transfer to a wire rack; let cool completely.

In the bowl of an electric mixer fitted with the whisk attachment, mix together 1 egg and flour on high speed until smooth. Add the remaining 9 eggs and continue mixing until well blended.

Place creme fraiche in a medium bowl and whisk until smooth; add milk and continue whisking until well combined. Add to mixer along with salt, pepper, and thyme; mix until well combined. Strain mixture into a large bowl through a fine mesh sieve.

Tightly pack Swiss chard leaves and cheese into prepared tart shell. Pour over egg mixture until tart shell is full (you may not need to use all of the egg mixture). Bake 20 minutes; reduce temperature to 325 degrees, and continue baking until filling is slightly firm, rather than liquid, and crust is a deep golden brown, 40 to 50 minutes more. Transfer quiche to a wire rack to cool until set, about 20 minutes. Serve warm or at room temperature. To reheat, cover quiche with aluminum foil and bake in an oven heated to 325 degrees for about 15 minutes.