Bring a large pot of water to a rolling boil. Add macaroni and cook for 5 minutes. Pasta will be slightly under cooked.
Spray slow cooker insert with nonstick cooking spray. Drain pasta and transfer to slow cooker. In the same pot the pasta was cooking in, melt butter over medium heat. Then stir in cheddar cheese soup, evaporated milk, salt, pepper, onion powder, garlic powder, and smoked paprika. Heat until warm, then stir in cream cheese. Once cream cheese is melted, stir in shredded cheddar cheese, 1 cup of colby jack cheese and parmesan cheese.
Transfer cheese sauce to slow cooker and mix with pasta. Cook on low for 2 1/2 hours, stirring every 30 minutes. For the last 30 minutes of cooking time, top with additional Colby Jack cheese, cover and let melt.
Tip: After each stir, use a damp paper towel to wipe excess cheese sauce from inside the upper edge of the slow cooker. This will make clean up easier later.