Step 1: Prepare the Puff Pastry
Preheat oven to 400°F (200°C).
Roll out puff pastry on a lightly floured surface until about 1/8-inch thick.
Cut into small rectangles, approximately 1 x 2 inches.
Arrange pastry rectangles on a parchment-lined baking sheet.
Prick each rectangle with a fork to prevent excessive puffing.
Sprinkle lightly with granulated sugar.
Bake for 10–12 minutes or until golden brown and crisp.
Transfer to a wire rack and cool completely.
Step 2: Make the Vanilla Whipped Cream
In a large bowl, combine heavy cream, powdered sugar, and vanilla extract.
Beat using an electric mixer until soft peaks form.
Avoid overwhipping to maintain a light, airy texture.
Step 3: Assemble the Mille-Feuille Cookies
Place one puff pastry rectangle on a serving surface.
Pipe or spoon whipped cream onto the pastry.
Add a second pastry layer and repeat with whipped cream.
Finish with a third pastry rectangle.
Top with an extra dollop of whipped cream and 2–3 fresh raspberries.
Garnish with fresh mint if desired.
Repeat with remaining pastry pieces.