Caramelized Onion & Gruyère Tart with Thyme
A sophisticated yet simple tart featuring a buttery crust filled with sweet caramelized onions, melted Gruyère, and fresh thyme, perfect for brunch or light dinner. This french-inspired recipe ready in about 55 minutes layers sheet (14 oz), thawed puff pastry, large, thinly sliced onions, butter into a dessert worth slowing down for — great for weekend baking, holiday tables, or any time you want a sweet payoff at the end of a meal. Each serving lands at about 320 calories and feeds 6, so it slots into a weekend bake or a special-occasion dessert tray. Tap "Plan a meal with the AI" below to drop this recipe into your week and send the ingredients straight to Instacart. Nutrition values are approximate, calculated from USDA FoodData Central (fdc.nal.usda.gov) — verify against ingredient labels for any health-driven dietary plan.
Ingredients
- 1 sheet (14 oz), thawed puff pastry
- 2 large, thinly sliced onions
- 2 tbsp butter
- 2 tbsp white wine
- 1 tbsp balsamic vinegar
- 1 cup, thinly sliced Gruyère cheese
- 1 tbsp fresh thyme leaves
- 1, beaten egg
- 1/2 tsp salt
- 1/4 tsp black pepper
Instructions
- Step 1: Preheat oven to 375°F. Roll out puff pastry on a lightly floured surface to fit a 9-inch tart pan. Press into pan and trim edges. Prick bottom with a fork. Chill while making filling.
- Step 2: Melt butter in a skillet over medium heat. Add onions and cook for 25-30 minutes, stirring occasionally, until deeply golden and caramelized. Add white wine and balsamic vinegar, scraping up browned bits, and cook for 2 more minutes.
- Step 3: Spread caramelized onions evenly over chilled pastry shell. Sprinkle with salt, pepper, and half the thyme.
- Step 4: Arrange Gruyère slices over onions. Brush pastry edges with beaten egg.
- Step 5: Bake for 25-30 minutes until crust is golden and cheese is bubbly. Cool for 10 minutes, then sprinkle with remaining thyme before slicing.
Equipment for this recipe
Top-rated tools to make this recipe successfully.
Frequently asked questions
How long does Caramelized Onion & Gruyère Tart with Thyme take to make?
Total time is about 55 minutes (25 min prep + 30 min cook). Most home bakers find this fits a weekend afternoon; chill or store as the recipe directs before serving.
How do I store leftover Caramelized Onion & Gruyère Tart with Thyme?
Cool fully before storing. Most baked desserts keep at room temperature in an airtight container for 2–3 days, or in the fridge for up to 5 days. Cream- or custard-based desserts must go in the fridge within 2 hours; reheat gently or serve cold per the recipe.
Can I substitute ingredients in Caramelized Onion & Gruyère Tart with Thyme?
Yes — most ingredients in this recipe have flexible swaps. For oil, use any neutral high-smoke-point oil (avocado, grapeseed, refined coconut). For aromatics, dried herbs at ⅓ the volume of fresh work in a pinch. The full ingredient list is shoppable on Instacart so you can see substitutes in real time.
How do I scale Caramelized Onion & Gruyère Tart with Thyme for a different number of people?
The recipe is written for 6 servings. Multiply each ingredient by (your serving target / 6). Cook time stays roughly the same up to 2x; for 3-4x batches, switch from a skillet to a sheet pan or stockpot so the food isn't crowded — overcrowding steams instead of browns.
What goes well with Caramelized Onion & Gruyère Tart with Thyme?
French mains like this pair well with a simple grain (rice, couscous, or crusty bread), a quick salad with acid (lemon vinaigrette, pickled onions), and a pan sauce or yogurt-based dip. Tap "Plan a meal with the AI" to get specific side suggestions.
What others are saying
- ★★★★☆
Good flavors but the sauce was a bit thin. I'd reduce it longer.
- ★★★★☆
Very good for a 30-minute recipe. Would bump up the spice level though.
- ★★★☆☆
Decent recipe but nothing special. Might try a different version.
