Place a large saucepan or skillet over medium heat and once it's hot add the butter. Melt it.
Add the flour and whisk until fully combined.
Still whisking, gradually add the milk, do not rush, and whisk continuously until fully combined.
Add onion powder, garlic powder, paprika, mustard powder, red pepper flakes, and salt.
Over medium heat, bring the mixture to a boil and simmer for about 2 minutes.
If desired, stir in sour cream until fully combined. Taste and adjust for salt and pepper.
Reduce heat to low and add cheddar cheese, Colby, and Parmesan. Stir to combine, until the cheese is fully melted.
Add to the cooked pasta and stir to combine.
Transfer the mixture to the prepared casserole dish.