For some reason, the scent of butter and onions browning on the stove top reminds me of autumn.
Perhaps it’s because that classic combination could be the base for so many dishes, the quintessential building block for the hearty soups that carry us through fall and winter.
Caramelized onions, with a hug of brown sugar or balsamic, also make for a rich topping that, this time of year, pairs well with squash. But caramelized onions elevate everything from burgers and pizza to grilled sandwiches, steak, risotto or pasta, even those blank canvases of dinner rolls and scones. Just fold them into the dough. Or, spoon some atop a toasted baguette round with a slice of brie as an appetizer or accompaniment for those hearty soups.
Here, caramelized onions top puff pastry for a dreamy appetizer that’s perfect for a crisp autumn afternoon or evening. The onions – golden, sweet and full of flavor – are complemented by the earthiness of the mushrooms, herbaceousness of the thyme, pungency of the garlic and creaminess of the cheese.
Buttery puff pastry rises up and forms little cups around the filling, hugging it in place. Make your own dough or save time – like I did this time – with the store-bought variety. That’s what the recipe calls for.
Serve these savory little bites at a harvest or Halloween party and keep on using the recipe throughout the holiday season. They would be wonderful at Thanksgiving, which will be here before we know it.
The creator called them “snappetizers” because of how quickly and easily they come together. The filling can be made a day ahead. And that’s what I did.
One of the loveliest things about preparing the onion mixture is the aroma it releases while it’s cooking. Might want to make a little extra. It’ll be difficult to resist sampling spoonfuls of the stuff before scooping it onto the pastry and popping it into the oven.
Gruyere, Mushroom and Caramelized Onion Bites
For the filling
4 tablespoons salted butter, divided
2 tablespoons vegetable oil, divided
5 to 6 ounces crimini or button mushrooms, sliced
2 medium yellow onions, thinly sliced
¼ teaspoon dried thyme
1 tablespoon sugar
1½ tablespoon balsamic vinegar
¼ teaspoon garlic powder
Salt and pepper, to taste
For the pastry
4 ounces grated Gruyere or apple wood smoked Gruyere cheese
1 (1-pound) package frozen puff pastry, thawed
1 egg, lightly beaten
In a large cast iron skillet over medium heat, heat 1 tablespoon of oil along with 1 tablespoon of butter. Add the mushrooms and sauté for about 5 minutes until tender. Remove and set aside in a medium bowl.
Heat the remaining 3 tablespoons of butter along with the 1 tablespoon of oil and sauté the onions for 5 minutes. Add the dried thyme and sugar and continue to cook for 25 minutes on medium low heat. Make sure to stir the mixture every 5 minutes or so. If the onions are caramelizing too fast, turn down the heat a little. Add the balsamic vinegar to deglaze the pan, allow the onions to soak it all in. Turn off heat. Add the onions to the mushroom mixture. Season with the garlic powder and salt and pepper to taste, then stir to combine. Allow to cool to room temperature. Mixture can be kept in an air-tight container and refrigerated for up to 48 hours at this point. Allow to come to room temperature before proceeding. Add the Gruyere cheese and mix well.
Position two racks in the upper and lower thirds of the oven. Preheat the oven to 400 degrees. Line 2 baking sheets with parchment paper or silicone mats. Using a knife or pizza cutter, cut the puff pastry into 2-inch squares and place them on a lined baking sheet. Make sure the puff pastry is cold before proceeding. If not, allow it to rest in the refrigerator for 10-15 minutes. Brush the beaten egg on the squares. Place a tablespoon of caramelized onion mixture in the center. Bake for 20-25 minutes, rotating the pan halfway in between until crisp and golden brown. Let cool slightly before serving.
Yield: about 30 to 34 bites
Notes: Make sure the puff pastry is cold when it goes into the oven. If at any point it becomes soft, allow it to rest in the refrigerator for 15-20 minutes or until it firms up again. Do not open the oven door during the first 10 minutes of baking time. Frequently opening the oven may cause the pastry to not puff up.