In a large skillet, heat 2 tablespoons of olive oil over medium heat. Add 2 large sliced onions with a pinch of salt, stirring occasionally for about 15-20 minutes until golden brown.

Transfer the onions to a bowl and let cool. Combine them with 1 pound of ground sausage, 1 teaspoon of fresh thyme, and salt and pepper. Optionally mix in ½ cup of Gruyère cheese or Dijon mustard.

Preheat your oven to 400°F (200°C) and line a baking sheet with parchment paper.

Roll out 2 sheets of puff pastry and cut into rectangles, roughly 4x6 inches. Add sausage mixture, fold pastry, seal edges, and crimp to prevent leakage.

Beat one egg and brush the tops of each roll with the egg wash.

Bake on the prepared baking sheet for about 20-25 minutes until golden brown.