Thaw the frozen puff pastry on the counter for about 30 minutes, until pliable but still cold.

Prepare the chocolate ganache by heating heavy cream in a saucepan until steaming. Pour it over the semi-sweet chocolate chips, let it sit for a couple of minutes, then stir until smooth. Allow to cool for 2 hours until thickened.

Make the cream cheese filling by beating the cream cheese, sugar, and vanilla together with a mixer until creamy and smooth.

Roll out the thawed puff pastry on a lightly floured surface. Cut the pastry into rectangles (6 per sheet) and gently score smaller grooves.

Spoon about 1 tablespoon of the cream cheese filling onto the center of each rectangle, ensuring not to touch the edges.

Refrigerate the filled pastries while preheating the oven to 400°F (200°C). Prepare an egg wash by mixing the egg and water together until smooth.

Brush the edges of the pastries with the egg wash, then place them onto lined baking sheets.

Bake for 17-20 minutes, or until they puff up and turn golden brown.

Spread the cooled chocolate ganache over the top of the cream cheese filling once the pastries have cooled slightly.