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Caramelized Onion Mushroom Apple Gruyere Bites

Caramelized onion mushroom apple Gruyere bites with jammy onions, browned mushrooms, and melted cheese in crisp mini phyllo shells. French-inspired and baked until the Gruyere bubbles over the toppings.
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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
Phyllo and cheese
  • 2 box (15 count each) mini phyllo shells 24 used
  • 1 cup shredded Gruyere
  • 0.5 fresh thyme for garnish

Equipment

  • 1 sheet pan
  • 1 cast iron skillet

Method
 

Caramelize the onions
  1. Melt butter in a cast iron skillet over medium-low heat, then add the thinly sliced onion and cook for 20-25 minutes, stirring often, until deep golden and jammy.
  2. Season the onions lightly with salt and pepper as they caramelize, keeping the heat at medium-low to avoid scorching.
Cook the mushrooms and apple
  1. Add the finely chopped cremini mushrooms and diced apple to the skillet and cook for 6-8 minutes, stirring occasionally, until the mushrooms are browned and their liquid evaporates.
  2. Stir in the thyme leaves and balsamic vinegar, then season with salt and pepper to taste.
Bake the phyllo bites
  1. Preheat the oven to 350F, then arrange the mini phyllo shells on a sheet pan.
  2. Fill each phyllo shell with the onion-mushroom-apple mixture, then top with shredded Gruyere.
  3. Bake for 8-10 minutes at 350F until the cheese is melted and the shells are crisp.
Finish and serve
  1. Garnish the baked bites with fresh thyme leaves, then serve warm.

Notes

For the most jammy filling, keep the onions at medium-low heat and stir frequently so they turn deep golden without burning. Store leftovers in an airtight container in the refrigerator for up to 3 days; reheat in a 325F oven until the phyllo shells crisp again. Freezing isn’t recommended because phyllo shells soften after thawing. For a lighter option, use reduced-fat Gruyere to cut calories while keeping the melty top layer.