Preheat your oven to 375°F (190°C) and line a baking sheet with parchment paper.

Roll out the thawed puff pastry sheet on a lightly floured surface until it's about 1/4 inch thick.

Using a heart-shaped cookie cutter, cut out as many hearts as you can from the puff pastry sheet.

Place a small dollop of Nutella in the center of half of the heart shapes, leaving a small border around the edges.

Brush the edges of the Nutella-topped hearts with beaten egg.

Place the remaining heart shapes on top of the Nutella-topped ones and gently press down the edges to seal.

Use a fork to crimp the edges of the hearts, ensuring they are securely sealed.

Brush the tops of the hearts with more beaten egg for a golden finish.

Place the filled hearts onto the prepared baking sheet and bake in the preheated oven for 12-15 minutes, or until puffed and golden brown.

Once baked, remove from the oven and allow to cool slightly before serving.

Optionally, dust the tops of the hearts with powdered sugar for an extra touch of sweetness.