In a mixing bowl, beat the egg with the sugar until light and fluffy.

Add the vanilla yeast, oil, and soft butter to the mixture, and mix until well combined.

Gradually add the flour and baking powder, mixing until a soft dough forms.

Knead the dough gently on a floured surface until smooth, then cover and let it rest for about 20 minutes.

In a saucepan, whisk the egg with the sugar and cornstarch until smooth.

Gradually add the milk, stirring constantly to avoid lumps.

Place the saucepan over medium heat and cook, stirring constantly, until the mixture thickens.

Once thickened, remove from heat and add the dark chocolate, stirring until fully melted and smooth.

Let the cream cool slightly, then stir in the sweetened cream until well combined. Allow the cream to cool completely.

Preheat your oven to 180°C (350°F) and line a baking sheet with parchment paper.

Roll out the dough on a floured surface to about 1/4 inch thickness.

Cut the dough into desired shapes (e.g., circles or squares).

Place a spoonful of the cooled chocolate cream in the center of each dough piece.

Fold the dough over the cream and press the edges to seal.

Place the pastries on the prepared baking sheet and bake for 15-20 minutes, or until golden brown.

Allow the pastries to cool slightly before serving.

Dust with powdered sugar or drizzle with melted chocolate if desired.