- 1 sheet premade puff pastry
- 2 yellow onions, sliced
- 1/2 Tablespoon butter
- 3/4 Cups Gruyere cheese
- fresh thyme
- freshly cracked black pepper
- balsamic vinegar
In a pan over medium-low heat, melt butter and add the sliced onions. Cook onions, stirring occasionally until colored a deep caramelized brown.
Preheat oven to 400 degrees.
Line a sheet tray with parchment and lay out puff pastry. Add onions and evenly spread them out making sure to reach the far corners.
Sprinkle of cheese, fresh thyme, a crack of ground pepper, and finish with a drizzle of balsamic vinegar.
Bake in oven for 40 minutes or until puffed and golden.