Season both sides of the chicken breasts generously with salt and pepper. Heat olive oil in a large skillet over medium-high heat. Once the oil shimmers, add the chicken and cook for 7-8 minutes per side until golden brown and the internal temperature reaches 165°F. Remove from the skillet and let rest on a plate.

In the same skillet, cook the bacon over medium heat until crispy, about 8-10 minutes. Transfer to a paper towel-lined plate and crumble once cooled. Pour off all but 1 tablespoon of bacon grease.

Add the sliced mushrooms to the skillet and sauté in the remaining bacon grease for about 5 minutes until golden brown around the edges and most of the liquid has evaporated.

Pour in the chicken broth and heavy cream, then add the garlic powder. Bring to a gentle simmer and cook for 2-3 minutes, stirring occasionally, until the sauce thickens slightly and reduces by about one-third.

Return the chicken breasts to the skillet and divide both shredded cheeses evenly over each piece. Spoon the creamy mushroom sauce over the cheese-topped chicken and cover with a lid. Cook for 2-3 minutes until the cheese is fully melted and bubbly. Garnish with crumbled bacon and chopped green onions before serving hot.