In a medium-sized pot, cook pasta according to package instructions, strain and then set aside (you can toss with olive oil to prevent the noodles from sticking together).
Return the pot to the stove and set flame to medium heat, add the butter and let it melt.
Whisk in the flour and cook for about 1 minute, stirring until the flour is cooked.
Slowly drizzle in the milk a little bit at a time, whisking really well each time.
Bring the milk mixture up to a simmer and then turn off the heat.
Add in the cheese. Stir the cheese and milk mixture until the cheese is fully melted and the sauce is creamy.
Add in the pasta, stir to combine, and season with salt and pepper to taste.