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Caramelized Onion Mushroom Apple Gruyere Bites

Caramelized onion mushroom apple gruyere bites in mini phyllo shells with deep golden, jammy onions and browned mushrooms, finished with bubbling melted gruyere. Baked until the cheese melts and the shells turn crisp, then topped with fresh thyme.
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Prep Time 15 minutes
Cook Time 40 minutes
Total Time 55 minutes
Servings: 24 servings
Course: Appetizer, Snack
Cuisine: French-inspired
Calories: 95
Ingredients Equipment Method Notes

Ingredients
  

Onion mixture
  • 2 tbsp butter
  • 1 yellow onion thinly sliced
  • 8 oz cremini mushrooms finely chopped
  • 1 apple finely diced
  • 1 tsp fresh thyme leaves
  • 1 tbsp balsamic vinegar
  • 0.25 salt to taste
  • 0.25 pepper to taste
Bites
  • 2 boxes (15 count each) mini phyllo shells 24 used
  • 1 cup shredded Gruyere
  • 1 fresh thyme for garnish

Equipment

  • 1 sheet pan

Method
 

Caramelize the onions
  1. Melt butter in a skillet over medium-low heat, then add the sliced yellow onion and cook 20-25 minutes, stirring often, until deep golden and jammy.
  2. Add the chopped cremini mushrooms and finely diced apple, then cook 6-8 minutes until the mushrooms are browned and the liquid evaporates.
  3. Stir in the fresh thyme leaves and balsamic vinegar, then season with salt and pepper to taste.
Bake the phyllo bites
  1. Preheat the oven to 350F and arrange the mini phyllo shells on a baking sheet.
  2. Fill each mini phyllo shell with the onion mixture, then top with shredded Gruyere.
  3. Bake 8-10 minutes, until the cheese is melted and the shells are crisp.
  4. Garnish with fresh thyme and serve warm, letting the bites cool just enough to handle.

Notes

For the crispiest shells, keep the onion mixture warm but not wet—if there’s extra moisture, cook 1-2 minutes longer until it looks jammy. Store baked bites in the refrigerator up to 2 days; re-crisp in a 350F oven for 5-7 minutes. These can be assembled (filled, unbaked) up to 1 day ahead and baked when ready. For a gluten-free swap, use gluten-free phyllo shells if available, keeping the bake time the same.