Preheat your oven to 350°F.
Grease the inside of a 9×9-inch square casserole dish or a 9x13-inch casserole dish with butter.
Heat the olive oil in a large skillet over medium-high. Season the chicken with salt and pepper and add to the hot skillet.
Cook until the chicken is no longer pink in the center, about 7-9 minutes. Transfer to the prepared casserole dish.
While the chicken is cooking, bring a medium saucepan filled 2/3rds of the way with water to a boil. Add the broccoli, cover, and cook for about 2 minutes or until bright green.
Drain and transfer to the casserole dish with the chicken, along with half of the crumbled bacon.
In a small bowl, mix the cream cheese, garlic, 1 cup of the cheddar cheese, and Hidden Valley Ranch dressing until well combined.
Spread the mixture evenly over the chicken and broccoli as best as you can.
Sprinkle on the remaining 1/4 cup of cheddar cheese and bacon.
Cover the casserole dish tightly with aluminum foil and bake for 20-30 minutes or until hot and bubbly.