1 sheet Dufour frozen all-butter puff pastry, thawed in refrigerator
3 organic peaches, cut into eighths (not soft-ripe, but not rock-hard)
1-1/2 tablespoons sugar
1-1/2 tablespoons Drillaud peach liqueur
1/2 cup (5 oz./155 g) Bonne Maman peach preserves
Preheat an oven to 400°F. Have ready a 10-inch square metal tart pan with a removable bottom.
On a lightly floured surface, roll out the puff pastry sheet into an 11-inch square and transfer to the prepared pan. Trim off the corners, then gather any dough overhang and press it into the sides of the pan to form a rim that is even in thickness. Using a fork, enthusiastically prick the bottom and sides of the dough. Place the tart shell in the freezer for 15 minutes. Remove from the freezer and bake until lightly golden, about 15 minutes. Let cool on a wire rack for about 30 minutes.
Note: If the crust has puffed and risen despite your best pricking efforts, gently press the enthusiastic pastry with the bottom of a half-cup measuring cup until it has become compliant.
Meanwhile, in a bowl, stir together the peaches, sugar, and peach liqueur. Let the mixture stand at room temperature for 15 minutes. (This can be done the night before)
Spread the peach preserves evenly over the bottom of the tart shell. Arrange the peach slices in three rows, and drizzle with any juices remaining in the bowl.
Bake until the peaches are tender, and the pastry is golden brown, 30 to 40 minutes.
Remove the tart from the oven. Let cool on a wire rack for about 1 hour. (The tart can be baked up to 4 hours in advance and cooled, then tented with aluminum foil and stored at room temperature.)
When ready to serve, let the pan sides fall away, then slide the tart onto a serving plate.
Serve with fresh whipped cream and perhaps a glass of prosecco?