Preheat the oven to 400℉ and spray a 9x13 inch baking pan or casserole dish with nonstick spray and set aside.
Add the mayonnaise, sour cream, garlic, olive oil, and ranch seasoning to a medium bowl; stir to combine.
1 cup mayonnaise, ¼ cup sour cream, 2 cloves garlic, 2 tablespoons olive oil, 1 ounce ranch seasoning
Stir in ¾ of the bacon, ¾ of the cheddar cheese, ¾ of the mozzarella cheese, and all the onion then set aside.
6 slices bacon, 1 cup cheddar cheese, 1 cup mozzarella cheese, ½ white onion
Place one of the chicken breasts onto a plate and cut deep holes into it using a knife, then spread the ranch mixture onto the chicken and push some of it into the holes.
4-5 chicken breasts
Place the chicken breast into the baking pan and repeat the process with the remaining chicken breasts and ranch mix.
Sprinkle on the remaining cheddar cheese, mozzarella cheese, and bacon; then loosely cover the pan with aluminum foil.
1 cup cheddar cheese, 1 cup mozzarella cheese, 6 slices bacon
Bake for 20 minutes then remove the aluminum foil and bake for another 10 minutes, or until the cheese starts to bubble around the edges and turn a light golden color.
Let the chicken rest for 10 minutes before serving with freshly chopped chives and additional bacon for garnish if desired.
Video
Notes
Storage: Store baked ranch chicken in an airtight container in the refrigerator for 3 days, or freeze for 3 months.