Go Back

Caramelized Onion Mushroom Apple Gruyere Bites

Caramelized onion mushroom apple Gruyere bites pair deeply golden onions, browned cremini mushrooms, and tender apple with flaky puff pastry. The savory-sweet filling and Gruyère bake into crisp, golden appetizer bites.
Print Recipe Pin Recipe
Prep Time 25 minutes
Cook Time 1 hour 2 minutes
Cooling 15 minutes
Total Time 1 hour 42 minutes
Servings: 24 servings
Course: Appetizer
Cuisine: American
Calories: 120
Ingredients Equipment Method Notes

Ingredients
  

For the filling
  • 2 tbsp unsalted butter
  • 2 yellow onions medium, thinly sliced
  • 0.5 tsp kosher salt
  • 8 oz cremini mushrooms finely chopped
  • 1 Granny Smith apple medium, cored and cut into 1/4-inch dice
  • 1 tsp thyme leaves fresh
  • 0.25 tsp black pepper
For the bites
  • 1 package (17.3 oz) frozen puff pastry thawed
  • 6 oz Gruyère cheese shredded
  • 1 egg large
  • 1 tsp water

Equipment

  • 1 12-inch skillet
  • 2 18x13-inch rimmed baking sheets

Method
 

Make the filling
  1. Melt the butter in a 12-inch skillet over medium heat, then add the onions and salt.
  2. Cook for 25-35 minutes, stirring often, until the onions are very soft and deeply golden.
  3. Add the mushrooms and cook over medium-high heat for 7-9 minutes, stirring often, until browned and their liquid has evaporated.
  4. Stir in the apple, thyme, and black pepper and cook for 3-4 minutes, until the apple is just tender.
  5. Transfer the filling to a plate and cool for 10 minutes.
Assemble and bake
  1. Heat the oven to 400°F.
  2. Line two 18x13-inch rimmed baking sheets with parchment paper.
  3. Unfold the puff pastry sheets and cut each into 12 equal pieces.
  4. Arrange 12 pieces on each prepared baking sheet, leaving about 1 inch between them.
  5. Score a 1/2-inch border around each piece without cutting all the way through, then prick the center several times with a fork.
  6. Beat the egg with the water in a small bowl and brush the borders with the egg wash.
  7. Divide the Gruyère among the pastry centers.
  8. Spoon the cooled filling evenly over the cheese.
  9. Bake for 18-22 minutes, switching the sheets between racks and rotating them front to back halfway through, until the pastry is puffed and golden.
  10. Cool on the baking sheets for 5 minutes before serving.

Notes

For the best texture, cool the filling before spooning it onto the pastry so the centers stay crisp. Refrigerate leftovers for up to 3 days; freeze baked bites for up to 2 months. For a vegetarian-friendly option, use Gruyère made with vegetarian rennet.