Mix the softened butter with the sugar and vanilla sugar.

Add the egg yolks, salt, flour, and baking powder, then knead into a soft dough.

Transfer the dough directly into the baking pan, spread it evenly, and form sides about 3 cm (1 1/4 inches) high. Place the pan in the refrigerator.

Blend the berries until smooth.

Take a small amount of the berry puree and mix it with the cornstarch until fully combined.

Pour the cornstarch mixture back into the remaining berry puree. Cook over medium heat, stirring constantly, until it comes to a boil. Continue cooking for 1 minute.

Add the sugar to the hot berry mixture and stir well.

Remove the pan from the refrigerator and bake the crust at 190°C (375°F) for 10–12 minutes.

Spread the berry filling over the crust and bake for another 10 minutes.

Beat the egg whites with a pinch of salt, gradually adding the sugar and vanilla sugar until stiff peaks form.

Spread the meringue over the pie and bake for another 10 minutes at 190°C (375°F).

Let the pie cool slightly before serving and enjoy!