Bacon Stuffed Mushrooms

Preheat oven to 375 degrees F (190 degrees C). (Prep time: 5 minutes)

Place bacon in a large skillet and cook over medium heat, turning occasionally, until crisp and evenly browned (approximately 8-10 minutes). Transfer bacon to paper towels to drain, reserving the bacon drippings in the skillet. Once cool enough to handle, crumble the bacon. (Cook time: 10 minutes)

Gently remove the stems from the mushrooms and set them aside. Place the mushroom caps, hollow sides up, on a baking sheet lined with parchment paper. Brush the insides of the mushroom caps with melted butter. (Prep time: 5 minutes)

Finely chop the mushroom stems. Add the chopped mushroom stems, black olives, green onion, and crumbled bacon to the skillet with the reserved bacon drippings. Cook over medium heat, stirring occasionally, until the mushroom stems soften and release their liquid (approximately 5 minutes). Add the minced garlic, salt, black pepper, and cayenne pepper (if using); stir to combine. (Cook time: 8 minutes)

Tilt the skillet slightly to pool the bacon drippings to one side. Whisk in the flour until smooth, creating a roux. Slowly pour in the milk, whisking constantly, until the gravy is smooth and thickened. Stir the vegetable-bacon mixture back into the gravy. Add the chopped Swiss cheese and Parmesan cheese; cook and stir until the cheeses are completely melted and the filling is creamy (approximately 3-5 minutes). (Cook time: 5 minutes)

Spoon the filling generously into the mushroom caps, mounding it slightly. (Prep time: 5 minutes)

Bake in the preheated oven until the mushrooms are tender and the filling is lightly golden brown (approximately 18-22 minutes). (Cook time: 20 minutes)

Remove the mushrooms from the baking sheet and let them cool on a platter for a few minutes before serving. Garnish with extra chopped green onion or a sprinkle of Parmesan cheese, if desired. (Cool time: 2 minutes)