Cook pasta according to package directions
Mix tuna fish, mushroom soup, milk, sour cream and ranch dressing all together
Add peas, garlic salt, and pepper; mix
Drain pasta and mix into casserole mixture
Put everything into an oven proof casserole dish
Bake in preheat 350 degree oven for 30 minutes
At the 20 minute mark, sprinkle with the cheese and then finish baking for 10 more minute
Serve, (half my family likes to eat it with ketchup)