These upside down onion tarts are a comforting, old-fashioned dish often served at church suppers and family gatherings. Sweet caramelized onions bake beneath a flaky crust, then flip into a beautiful, savory tart that’s rich, soft, and deeply flavorful.
Ingredients
- 2 large yellow onions, thinly sliced
- 3 tablespoons unsalted butter
- 1 tablespoon olive oil
- 1 tablespoon brown sugar
- 1 teaspoon balsamic vinegar
- 1/2 teaspoon salt
- 1/4 teaspoon black pepper
- 1 teaspoon fresh thyme or 1/2 teaspoon dried thyme
- 1 sheet puff pastry or refrigerated pie crust, thawed
- 1/2 cup shredded Gruyère or Swiss cheese (optional)
Instructions
1. Preheat the Oven
Preheat your oven to 375°F (190°C). Lightly grease a muffin tin or small tart pan.
2. Caramelize the Onions
In a large skillet over medium heat, melt the butter with the olive oil.
Add the sliced onions and cook slowly, stirring often, for 15–20 minutes until soft and golden.
Stir in the brown sugar, balsamic vinegar, salt, pepper, and thyme.
Cook for 2 more minutes, then remove from heat.
3. Assemble the Tarts
Spoon the caramelized onions evenly into the bottom of each muffin cup or tart mold.
If using cheese, sprinkle a small amount over the onions.
Cut the puff pastry or pie crust into circles slightly larger than each cup.
Place dough on top of the onions, gently tucking the edges down inside.
4. Bake
Bake for 20–25 minutes, or until the pastry is puffed and golden brown.
5. Invert and Serve
Let the tarts rest for 5 minutes.
Carefully invert onto a serving plate so the onions are on top.
Serve warm.
