Preheat oven to 350°F.
Grease the inside of a 9×9-inch square casserole dish or a 9x13-inch casserole dish with butter or cooking spray.
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.
4 cups broccoli florets
Add the diced bacon to a large skillet over medium heat. Cook until crisp, then remove with a slotted spoon to a paper towel-lined plate. Carefully drain all but 1 tablespoon of the bacon grease from the pan and return the pan to the stove top.
6 slices bacon
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.
1 1/2 pounds chicken, salt, pepper
Add the chicken and half of the bacon to the casserole dish with the broccoli.
Return the pan to the stove top and add the garlic. Cook for 30 seconds, then add the cream cheese, 1 cup of the cheddar cheese and the ranch dressing. Mix well.
2 cloves garlic, 8 ounces cream cheese, 1 1/2 cups cheddar cheese, 1/2 cup ranch dressing
Spread the mixture evenly over the chicken and broccoli as best as you can. Don't worry if it's not perfect, it will melt more as it heats up in the oven.
Sprinkle on the remaining 1/2 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.