In a large skillet, heat 2 tablespoons of olive oil and 2 tablespoons of butter over medium heat. Add 4 sliced yellow onions and cook for approximately 30 minutes until golden brown.

Stir in 1 cup of beef broth and 1 tablespoon of white vinegar and let the mixture simmer for about 5 minutes.

Preheat your oven to 375°F (190°C). Unroll a tube of crescent roll dough onto a lightly floured surface and cut into 3x3 inch rectangles, pressing into a greased mini muffin tin.

Spoon the caramelized onion mixture into each dough cup, leaving space for the cheese, then sprinkle with grated Gruyère cheese.

Bake for 18-20 minutes until the dough is puffed up and golden brown and the cheese is melted.

Remove the bites from the muffin tin, garnish with fresh thyme, serve warm, and enjoy!