Step 1
Preheat oven to 375 degrees F (190 degrees C). Line a baking sheet with parchment paper. Arrange chicken on the baking sheet.
Step 2
Bake chicken in the preheated oven until no longer pink in the center and the juices run clear about 30 minutes. An instant-read thermometer inserted into the center should read at least 165 degrees F (74 degrees C).
Step 3
Dice chicken and place in a bowl; add ranch mix and stir until coated.
Step 4
Place bacon in a large skillet and cook over medium-high heat turning occasionally until evenly browned about 10 minutes. Drain bacon slices on paper towels reserving bacon grease in the skillet. Crumble bacon into small pieces.
Step 5
Heat reserved bacon grease in the skillet; cook and stir bell pepper until slightly tender 2 to 3 minutes. Add chicken 1 jar Alfredo sauce milk and garlic; cook and stir until heated through about 5 minutes.
Step 6
Bring a large pot of lightly salted water to a boil; add penne and cook stirring occasionally until tender yet firm to the bite about 11 minutes. Drain.
Step 7
Pour 1/2 the jar of remaining Alfredo sauce into a casserole dish; top with 1/2 of the penne 1/2 of the chicken mixture 1 1/2 cup mozzarella cheese and 1/2 of the bacon. Repeat layering with remaining ingredients in the same order ending with 1 cup mozzarella cheese and bacon on top.
Step 8
Bake in the preheated oven until casserole is bubbling and cheese is lightly browned about 30 minutes.