Start pasta - cook according to package directions. (I’m sure you can do it!)
In a large pot over low heat combine milk, flour, salt, and pepper. Stir until smooth and blended. (Don’t let the sauce boil. If it does, the milk will curdle.)
Add in cheddar, butter, and blue cheese. Stir slowly until sauce thickens and butter and cheese melt. Once the sauce is blended, throw in your pasta.
Serve right away and enjoy!
Note: When the pasta gets cold your sauce will thicken considerably. Just reheat the pasta and serve again!