Caramelized Onion, Mushroom & Gruyere Tartlets

This year's Cookie Exchange Sunday Dinner I wanted to prepare some fancy pants appetizers.  I usually do a dip or some sort, or have friends bring the appetizers. But I stumbled onto this recipe from the Brown Eyed Baker (again with the Brown Eyed Baker site) and just had to make this.

It is time consuming to make the "filling" but it's very much worth that time.  The outcome was spectacular and delicious!  I'll make these again for sure.

The only issue with mine that I had were the puff pastry didn't puff so much.  Many of them were flat, but still tasty.  I think they may have been too small and too much good stuff on top of them. Next time I'll make them slightly bigger.


Photo courtesy of
The Brown Eyed Baker

Caramelized Onion, Mushroom & Gruyere Tartlets
Recipe from The Brown Eyed Baker

Yield: 16 3-inch tartlets; [JW note: I made mine an inch and I got 24 of them]

1 T olive oil
1 large yellow onion, thinly sliced
1 T unsalted butter
16 ounces white button mushrooms, thinly sliced
1 clove garlic, chopped
½ tsp dried thyme
Salt and pepper, to taste
¼ c white wine (can substitute chicken or vegetable broth)
2 sheets puff pastry (thawed according to directions on package)
1 cp shredded Gruyere cheese (can substitute any variety of Swiss cheese)
1 egg + 1 tablespoon water, beaten together (for the egg wash)
Handful of parsley, chopped

Preheat oven to 400 degrees F and line two baking sheets with parchment paper.

Heat the olive oil in a wide, heavy-bottomed pan over medium-low heat and add the onions. Cook, stirring occasionally, until they begin to caramelize, about 20 minutes.

Add the butter to the pan. Once melted, add the mushrooms and sauté, stirring occasionally, until they are completely soft and all of the liquid evaporates, about 20 minutes.

Add the garlic and the thyme and saute until fragrant, about 1 minute. Season with salt and pepper to taste.

Add the wine, scraping the bottom of the pan to pull up all of the browned bits, and cook until all of the liquid has evaporated. Remove from heat.

Unfold the thawed sheets of puff pastry and cut out circles from the dough, placing them evenly spaced on the baking sheets. Using a very sharp knife, make four small scores around the perimeter of the dough, about ¼ to ½-inch from the edge.

Top the rounds of puff pastry with a small spoonful of the onion and mushroom mixture, trying to keep the filling within the score marks. Top with the shredded Gruyere cheese. Brush the edges of the dough rounds with the egg wash.

Bake until the pastry is golden brown, about 15 to 25 minutes. Garnish with fresh chopped parsley.