Print this Recipe

These bite-sized tartlets capture all the comforting, caramelized richness of French onion soup in a crispy, buttery shell. Perfect as an appetizer or an elegant party snack.

🛒 Ingredients (Servings: 12 tartlets)

• 2 tbsp unsalted butter
• 2 large yellow onions, thinly sliced
• 1 tsp sugar
• 1 tbsp balsamic vinegar
• 1 tsp fresh thyme leaves (or ½ tsp dried)
• Salt and black pepper, to taste
• ½ cup grated Gruyère cheese
• 1 sheet frozen puff pastry, thawed
• 1 egg, beaten (for egg wash)
• Fresh chives, finely chopped (optional garnish)

🍳 Instructions:

1️⃣ Caramelize the Onions:
🧅 In a skillet over medium heat, melt the butter. Add sliced onions and sugar. Cook slowly, stirring often, for 25–30 minutes until deeply golden. Stir in balsamic vinegar, thyme, salt, and pepper. Cook 5 more minutes and let cool.

2️⃣ Prepare the Pastry:
🥐 Roll out the puff pastry sheet on a floured surface. Cut into 12 squares or circles using a cookie cutter or knife. Press into mini muffin tins or onto a parchment-lined baking sheet.

3️⃣ Fill the Tartlets:
🥄 Spoon a generous amount of the caramelized onion mixture into each pastry cup. Top with shredded Gruyère cheese.

4️⃣ Brush and Bake:
🔥 Brush pastry edges with the beaten egg for a golden finish. Bake at 400°F (200°C) for 18–22 minutes or until the pastry is puffed and golden brown.

5️⃣ Garnish and Serve:
🌿 Sprinkle with fresh chives if desired. Serve warm and enjoy the irresistible aroma and flavor.

🛍️ Amazon Must-Haves to Help You Create the Best French Onion Tartlets

• 🍳 Nonstick Mini Muffin Pan – Ideal for tartlet shaping and even baking.
• 🔪 Mandoline Slicer – For ultra-thin, uniform onion slices.
• 🥄 Silicone Spatula Set – Great for caramelizing and scooping.
• 🧈 Puff Pastry Sheets – Keep some frozen sheets on hand.
• 🧀 Cheese Grater – Get the perfect Gruyère shred.
• 🍽️ Elegant Serving Tray – Present your tartlets with flair.

💡 Helpful Tip:

Make the caramelized onion filling ahead of time—it actually gets more flavorful overnight. Just reheat slightly before assembling your tartlets for baking!