Caramelized Onion-Apple Bites

These savory snacks can be prepared in advance and are perfect for a casual meal. Cooking time: 1 1/2 hours. Notes: Onion and apple topping can be prepared 2 days in advance. Triangles can be prepared, covered and cooled in the morning before the party, and then sent to the oven when guests arrive. They can also be frozen, well wrapped, for up to 3 months (do not defrost before baking).
Melt the butter in a large skillet over medium-high heat. Add the onion and 1/2 tsp salt. Cook, stirring occasionally, until the onion is tender, about 5 minutes. Add the apples and stir to coat. Reduce the heat to medium and cook, stirring frequently, until the onion is medium brown, about 30 minutes. Add pepper and salt to taste. Set aside and let cool for about 10 minutes.Preheat the oven to 375 degrees. Unfold the puff pastry sheet. Cut the sheet into 16 squares, then cut these squares in half diagonally to make 32 triangles. Place them, without touching, on a baking sheet.Place a spoonful of the cooled onion-apple mixture on each triangle. Top with grated cheese and chopped thyme. Bake until fluffy and golden brown, 15 to 20 minutes. Serve hot.Note: A nutritional analysis is provided for each triangle.