Melt butter in a small saucepan over medium heat. Add flour and whisk until smooth. Gradually add warm milk, whisking constantly, until the mixture thickens into a paste-like sauce. Season with salt and pepper. Let it cool completely before using.

If the passata is thin, simmer it for 5–10 minutes until it clings to a spoon. Cool slightly.

Work with cold dough. Cut out larger base circles (about 10 cm) and slightly smaller tops (about 8 cm). You can use pastry rings or cups as guides.

Place a base disc on a parchment-lined tray. Brush lightly with egg. Spoon a small amount of béchamel in the center, top with a few mozzarella cubes, then a teaspoon of thick passata. Don’t overfill and leave a clean edge all around.

Place a smaller pastry disc on top, pressing gently around the filling (not the rim). Brush the top with egg wash. Chill the assembled pastries in the fridge for 45–60 minutes before baking. This step helps them puff nicely and keeps the filling inside.

Preheat the oven to 200°C / 400°F. Bake for 15–25 minutes, depending on size, until golden brown and puffed.

Let them rest for a few minutes so the filling sets. Serve warm or at room temperature.