The Secret’s on the Bottom: Irresistible Upside-Down Onion Tarts
Move over quiche and say hello to the showstopper your brunch table’s been missing — Upside-Down Onion Tarts. These flaky, caramelized beauties flip traditional tarts on their head (literally) and deliver bold, savory flavor with a touch of elegance. Whether served as an appetizer, side dish, or centerpiece, they’re guaranteed to wow.
Let’s dive into how to create these golden gems — and what tools and ingredients will make the process a breeze.
🧂 Ingredients (Makes 6 individual tarts or 1 large tart)
- 3 large red or yellow onions, peeled and sliced into ½-inch rounds
- 2 tbsp olive oil
- 2 tbsp butter
- 2 tbsp balsamic vinegar
- 1 tbsp brown sugar
- 1 tsp fresh thyme leaves (or ½ tsp dried)
- Salt and freshly cracked black pepper, to taste
- 1 sheet of puff pastry, thawed if frozen
- 1 egg (for egg wash)
Optional toppings:
- Goat cheese or feta crumbles
- Fresh arugula for serving
🥄 Instructions
Preheat your oven to 400°F (200°C).
Prep your muffin tin or tart pan by lightly greasing the cups.
Caramelize the onions: In a skillet, heat the butter and olive oil over medium heat. Add onion slices in a single layer and cook until golden, about 8–10 minutes per side. Carefully flip to caramelize both sides.
Deglaze and season: Add balsamic vinegar, brown sugar, thyme, salt, and pepper. Let simmer for 2–3 minutes until syrupy. Remove from heat.
Assemble the tarts: Place a caramelized onion round at the bottom of each muffin cup or tart mold, spooning a little of the vinegar mixture over each.
Cut the puff pastry: Cut the pastry sheet into circles slightly larger than each onion. Place over the onions and tuck in the edges gently.
Egg wash & bake: Brush the tops with beaten egg and bake for 20–25 minutes until puffed and golden.
Flip and serve: Let the tarts cool for 5 minutes, then carefully invert them onto a plate so the onions are on top. Top with goat cheese or arugula if desired.
📦 Amazon Must-Haves for Caramelized Onion Tartlets
- 🍳 Nonstick Muffin Pan – Ideal for baking perfectly portioned tartlets with easy release.
- 🔪 Mandoline Slicer – Achieve even, thin onion slices for consistent caramelization.
- 🍯 Balsamic Vinegar Glaze – Adds rich, sweet depth to your onions.
- 🥐 All-Butter Puff Pastry Sheets – Flaky, golden layers start with quality dough.
- 🍴 Mini Tart Tins with Removable Bottoms – For elegant presentation and effortless removal.
- 🌿 Fresh Thyme Plant Kit – Keep this aromatic herb handy in your kitchen garden.
🧄 Why You’ll Love It
These tarts hit that sweet-and-savory spot thanks to rich caramelized onions balanced by tangy balsamic and flaky pastry. They’re versatile, too — serve them warm, room temp, or cold. Great for brunches, dinner parties, or even meal prep with a fancy twist.
Plus, flipping them upside-down at the end? Chef’s kiss moment.