Step 1

Preheat the oven to 375°F. In a 12-inch skillet, cook the bacon over medium heat, stirring often until crispy, about 8 minutes. Remove the bacon from the pan using a slotted spoon. Set aside, leaving drippings in pan.

Step 2

Add the onion and garlic to the drippings; cook, stirring often, until slightly softened, about 5 minutes. Whisk in the cream cheese, milk, ranch seasoning mix, and 1 cup of the mozzarella until smooth; remove from the heat.

Step 3

In a large bowl, stir together the ranch mixture, cooked pasta, chicken, pimientos, and ½ cup of the green onion until well combined. Transfer to a 13x9-inch casserole dish. Sprinkle evenly with the bacon; top with the remaining 2 cups mozzarella.

Step 4

Bake until the top is golden brown and crispy, 25-30 minutes. Let cool slightly; garnish with more green onion just before serving, if you like.