Preheat your oven to 400°F (200°C).

Chop 10 oz. of baby bella mushrooms and set aside. Slice remaining 4 oz. for topping.

Slice pockets into each chicken breast, ensuring not to cut all the way through.

In a skillet, add 2 tablespoons of olive oil and sauté chopped mushrooms for about 5 minutes until golden.

Add diced onion to the skillet and sauté for an additional 3 minutes.

Incorporate dried parsley, minced garlic, dried thyme, salt, and pepper; cook until fragrant.

Combine sautéed mixture with 1 cup of shredded Gouda cheese in a mixing bowl.

In the same skillet, add 2 tablespoons of olive oil, brown the chicken breasts for 2 minutes on each side.

Stuff each chicken pocket with the mushroom and Gouda mixture, and place in a greased baking dish.

Bake the stuffed chicken for 50 minutes.

Sauté sliced mushrooms in the skillet for about 2 minutes to create a topping.

After baking, top chicken with remaining Gouda cheese and sautéed mushrooms. Return to oven for 7-10 minutes until cheese is melted.