Line a baking tray with parchment (baking) paper.

On a lightly floured cold surface, roll out the puff pastry dough into a 16x9-inch sheet. Cut horizontally to form four 4x9-inch strips. Then, cut each strip into three equal portions to get a total of twelve 4x3-inch rectangles. Place the rectangles on the prepared tray and gently pierce the sheets with a fork a few times. Cover the tray and refrigerate for 20 minutes.

Preheat the oven to 205°C/400°F. Brush the rectangles with egg wash and bake until golden brown, about 20-25 minutes. Transfer the puffs to a wire rack and let cool. Store in an airtight container for up to a week or process further.

Whip the heavy cream with powdered sugar, vanilla essence and gelatin, if using, to form stiff peaks. On one of the puffs spread about 2-tbsp of the cream. Evenly layer the strawberries. Place another rectangle puff on the top and similarly spread cream and strawberries. Top with the final rectangle puff. Garnish with a few strawberries, a teaspoon of cream and some powdered sugar.

Refrigerate for at least 1 hour up to 3-4 hours and serve.

Variations: Pastry: Do not pierce the sheets. Refrigerate and bake as directed in the recipe. When ready to use, split the sheets into two layers by slicing through the center with a serrated knife. Thus, you will get twenty-four 4X3-inch rectangles. Fill as directed.
Filling: Try thick custard or sweetened-curd in place of whipped cream and different berries in place of strawberries.