Preheat your oven to 400°F. Line a baking tray with parchment paper. Lightly flour your work surface. Place the thawed puff pastry on it. Roll gently to smooth any folds without making the pastry too thin.

Use a sharp knife to cut the pastry into eight equal rectangles. Keep the cuts clean for even baking. Place each piece on the prepared baking tray. Leave some space between the pieces because the pastry will expand.

Sprinkle the pastry pieces lightly with granulated sugar. Press the sugar gently into the surface. This creates a delicate sweetness and helps the pastry develop a beautiful golden finish while baking.

Place the tray in the preheated oven. Bake for about 16 to 18 minutes. The puff slices should rise nicely and become golden brown. Avoid opening the oven too often because sudden temperature changes can affect the pastry.

Remove the baked pastry from the oven. Let the slices cool completely on a wire rack. Do not add whipped cream while they are warm. Heat can quickly melt the cream and make your dessert messy.

Pour chilled heavy cream into a clean mixing bowl. Add powdered sugar and vanilla extract. Beat with an electric mixer until soft peaks form. Stop mixing once the cream becomes fluffy and holds its shape.

Carefully split each pastry rectangle in half horizontally. Pipe or spoon whipped cream onto the bottom piece. Add a few sliced strawberries. Place the pastry top gently over the cream without pressing too hard.

Dust the finished puff slices with powdered sugar. Add a small strawberry slice on top if desired. Serve immediately for the best contrast between crisp pastry and creamy filling.