Cook the elbow macaroni according to package instructions until al dente. Drain and set aside.
In the crockpot, combine the cooked macaroni with the cubed butter.
Add the milk and stir gently to combine.
Mix in the shredded cheddar and grated Parmesan cheese.
Sprinkle in the garlic powder, onion powder, salt, pepper, paprika, and mustard powder.
Stir everything together until the cheese starts to melt.
Cover the crockpot and cook on low for 2-3 hours or on high for 1-2 hours.
Stir occasionally to prevent sticking.
Once the cheese is fully melted and creamy, serve hot.