Mushroom Tartlets

Why You’ll Love This Recipe

I really enjoy how these tartlets layer sweet and savory flavors in a single bite. The caramelized onions add richness, the mushrooms bring earthiness, and the Grand Cru cheese melts into everything with a nutty depth. The puff pastry makes them flaky and golden, and they’re just the right size to serve as an appetizer, snack, or light meal with a salad.

Ingredients

(Note: All ingredient amounts are listed in the recipe card below.)

1 sheet puff pastry thawed according to package instructions
2 large onions chopped
2 tablespoons olive oil
¼ teaspoon salt
1 teaspoon dark brown sugar
8 ounces mushrooms thinly sliced
2 garlic cloves pressed
2 tablespoons dried thyme
1 egg plus 1 tablespoon water beaten together
¾ cup Roth Grand Cru cheese shredded

Directions

I start by preheating my oven to 400°F (200°C). While that warms up, I set a skillet over medium heat, add olive oil, and sauté the chopped onions with the salt until they begin to soften. I stir in the brown sugar and let the onions cook slowly until they’re golden and caramelized, which usually takes about 15–20 minutes.

Next, I add the sliced mushrooms and garlic, cooking until the mushrooms release their moisture and everything reduces down. I stir in the dried thyme for a warm, fragrant note.

I roll out the puff pastry on a lightly floured surface and cut it into squares or circles, depending on the look I want. I place the pastry pieces on a parchment-lined baking sheet, then spoon the onion and mushroom mixture evenly over the top, leaving a small border around the edges. I sprinkle the shredded Grand Cru cheese over each tartlet.

I brush the exposed pastry edges with the egg wash for a golden finish, then bake for 15–20 minutes, or until the pastry is puffed and golden brown. I let the tartlets cool for a few minutes before serving.

Servings and Timing

I usually get 6 to 8 tartlets from one sheet of puff pastry, depending on how I cut them. Prep time takes about 20 minutes with the caramelization of onions, and baking takes another 15–20 minutes. Altogether, these tartlets are ready in around 35–40 minutes.

Variations

Sometimes I swap Roth Grand Cru for Gruyère, fontina, or sharp cheddar if I want a different cheese flavor. I also enjoy mixing in fresh herbs like rosemary or sage in place of thyme for variety. Adding a splash of balsamic vinegar to the onions while caramelizing gives a tangy depth. For extra indulgence, I’ve even topped the tartlets with a drizzle of truffle oil just before serving.

Storage/Reheating

I keep leftover tartlets in an airtight container in the refrigerator for up to 3 days. To reheat, I place them in a 350°F (175°C) oven for about 8–10 minutes until warmed through and crispy again. I avoid the microwave, since it softens the pastry.

FAQs

Can I make these tartlets ahead of time?

Yes I prepare and bake them ahead, then store them in the fridge. When ready to serve, I reheat in the oven until crisp.

Can I freeze mushroom tartlets?

I’ve frozen them after baking by cooling completely and wrapping tightly. To serve, I bake them straight from frozen at 350°F until heated through.

Can I use fresh thyme instead of dried?

Absolutely I just use about 2 teaspoons of fresh thyme instead of 2 tablespoons dried for a more delicate flavor.

What is Roth Grand Cru cheese?

It’s a Wisconsin cheese similar to Gruyère, with a nutty, complex flavor that melts beautifully. It really elevates the tartlets.

Can I add other vegetables?

Yes sometimes I add spinach, roasted red peppers, or even a few sun-dried tomatoes to change up the flavors.

How thin should I slice the mushrooms?

I slice them thinly, about ⅛ inch thick, so they cook down quickly and blend well with the caramelized onions.

Can I use store-bought caramelized onions?

If I’m in a rush, yes but I prefer making my own for fresher, richer flavor.

Do I need to blind-bake the pastry first?

No, these bake up nicely without blind baking, as long as I don’t overload the pastry with too much filling.

Can I make one large tart instead of individual tartlets?

Definitely I just roll the pastry into a rectangle, spread the topping over, and slice into squares after baking.

What should I serve with mushroom tartlets?

I like pairing them with a crisp green salad, roasted vegetables, or even soup for a cozy meal.

Conclusion

These mushroom tartlets are one of my favorite recipes for when I want something flaky, savory, and full of flavor. With caramelized onions, mushrooms, and nutty cheese on puff pastry, they’re always a hit at gatherings and just as enjoyable for a quiet dinner at home.

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