1 tablespoon olive oil
1 small yellow onion, diced
salt to taste
2 Tbs. unsalted butter
1/2 pound apples (about 2-3 apples), peeled and diced (I used honeycrisp)
1 teaspoon sugar
1 ounce Gruyère cheese, grated
2 Tbs. minced fresh chives
1 sheet frozen puff pastry dough, thawed
1 egg, beaten with 1 tablespoon water
Full recipe from : yummly.co
In a non-strick fry pan over medium heat, heat the olive oil. Add the onions and season with salt, stirring occasionally, until the onions are golden brown, about 10-15 minutes. Transfer to a mixing bowl and set aside.
Preheat oven to 400 degrees F. Melt the butter in the fry pan over medium heat. Add the apples and sugar and stir to coat the apples. Cook until the apples are soft and start to caramelize, about 5 minutes. Transfer to the bowl with the onions and stir in the cheese and chives. Season with more salt to taste. Set aside.
Prepare a baking sheet with parchment paper or a baking mat. Cut the puff pastry into 2-inch squares and place on the baking sheet, spacing the squares about 1 inch apart. Brush the pastry squares with the egg and water mixture and spoon a heaping tablespoon of the filling in the center of each square.
Bake until the pastry is crisp underneath and golden brown on top, about 20-25 minutes. Serve at room temperature.