Savory Mushroom Onion Tart (Printable)
Flaky tart featuring caramelized onions, earthy mushrooms, and creamy cheese with fresh herb garnish.
# What You'll Need:
→ Pastry
01 - 1 sheet (8.8 oz) ready-made puff pastry, thawed
→ Vegetables
02 - 2 tablespoons olive oil
03 - 1 tablespoon unsalted butter
04 - 2 large yellow onions, thinly sliced
05 - 14 oz cremini or button mushrooms, sliced
06 - 2 cloves garlic, minced
→ Filling
07 - 3 large eggs
08 - 2/3 cup heavy cream
09 - 1 cup grated Gruyère or Swiss cheese
10 - 1 tablespoon fresh thyme leaves or 1 teaspoon dried
11 - 1 teaspoon salt
12 - 1/2 teaspoon black pepper
→ Garnish (optional)
13 - Fresh chives or parsley, chopped
# Directions:
01 - Preheat oven to 400°F. Line a 9-inch tart pan with parchment paper. Roll puff pastry and press into the tart pan. Trim excess and prick base with fork. Chill while preparing filling.
02 - Heat olive oil and butter over medium heat in a skillet. Add onions and cook, stirring occasionally, until soft and golden, about 12 minutes.
03 - Add mushrooms to onions, cooking 8-10 minutes until moisture evaporates and mushrooms brown. Stir in garlic and thyme, cook 1 more minute. Remove from heat and cool slightly.
04 - Whisk eggs, heavy cream, salt, and pepper in a bowl. Fold in grated cheese until combined.
05 - Spread onion-mushroom mixture evenly over chilled pastry shell. Pour egg and cheese mixture on top.
06 - Bake tart for 25-30 minutes until filling is set and pastry is golden brown.
07 - Let tart cool for 10 minutes. Garnish with chopped fresh chives or parsley. Slice and serve warm or at room temperature.
# Cooking Tips:
01 -
- The pastry stays crisp while the filling turns silky and rich—it's the texture contrast that keeps you reaching for another slice.
- Caramelized onions do the heavy lifting here, transforming from sharp to almost sweet with minimal effort, making the whole dish feel more luxurious than it actually is.
02 -
- Don't skip the chilling step for the pastry, and don't skip the slow cooking of the onions—both are what separate a good tart from a transcendent one.
- If your oven runs hot, watch the pastry edges after 20 minutes and tent them with foil so they don't burn while the filling sets.
03 -
- Buy pre-made puff pastry and you've already won half the battle; there's no shame in shortcuts that free you to focus on the vegetables.
- Taste the onion-mushroom mixture before it goes into the tart and adjust the seasoning—this is your last chance, and good seasoning at this step carries through the whole dish.