1. Preheat oven to 400°F (200°C). Line a baking sheet with parchment paper.

2. Roll puff pastry slightly if needed, place on the sheet, and prick lightly with a fork.

3. Bake 15–18 minutes until puffed and golden. Cool completely.

4. Warm 2 cups milk in a saucepan until hot but not boiling.

5. In a bowl, whisk egg yolks, sugar, and cornstarch until smooth and pale.

6. Slowly whisk warm milk into the egg mixture (temper), then pour everything back into the saucepan.

7. Cook over medium heat, whisking constantly, until thick and smooth (about 3–6 minutes).

8. Remove from heat; stir in butter and vanilla. If too thick, whisk in 1–2 tbsp milk.

9. Cover custard with plastic wrap touching the surface and chill at least 30 minutes.

10. Cut cooled puff pastry into small squares or rectangles (about 2–3 inches each).

11. Assemble: pastry layer + custard + pastry layer (2–3 layers total). Repeat.

12. Dust with powdered sugar; drizzle chocolate if desired. Add berries/mint and serve.