Caramelized Onion Tarte Tatin

Instructions

1. 1
   Preheat oven to 400°F (200°C). Roll puff pastry to fit your skillet and refrigerate.
2. 2
   In a 10-inch oven-safe skillet, melt butter with olive oil over medium heat. Add onion rounds in a single layer, sprinkle with sugar, salt, and pepper. Cook undisturbed for 8 minutes.
3. 3
   Flip onions, add thyme, and cook another 12-15 minutes, stirring occasionally, until deeply golden. Add balsamic vinegar, cook 2-3 minutes until jammy. Remove from heat.
4. 4
   Lay puff pastry over onions, tuck edges down, and cut 2-3 vents in the top.
5. 5
   Bake 20-25 minutes until pastry is deep golden and crisp. Let rest 5 minutes.
6. 6
   Invert tart onto a plate. Serve warm, garnished with fresh thyme.