You can make smaller tarts with extra puff-pastry dough after cutting: Use two or three pieces of stone fruit and bake about 20 minutes. The leftover frangipane, or almond mixture, is a great addition to French-toast batter.
Pulse almonds in a food processor until finely ground. Add granulated sugar, butter, 1 egg, salt, and cinnamon; process until smooth.
Preheat oven to 400 degrees. Whisk remaining egg with 1 tablespoon water. On a lightly floured surface, cut pastry into 6 four-inch-squares and transfer to a parchment-lined baking sheet. Brush edges of pastry with egg wash. Spread 2 teaspoons almond mixture in center of each square; top with 4 pieces fruit. Sprinkle each tart with some turbinado sugar.
Bake until tarts are golden brown and fruit has softened, 22 to 25 minutes. Let cool on a wire rack, 20 minutes. Sprinkle with flowers; serve.