Put a large pot of salted water on to boil for the pasta. Once the water is boiling rapidly, add your pasta and stir to separate. Cook according to package directions until au dente, usually 8-10 minutes, meaning it will still have a slight chewiness.
Meanwhile, In another large pot over medium high heat, melt the butter.
Add the flour and whisk until smooth. Continue whisking for another 2-3 minutes, letting it bubble and thicken. Slowly whisk in the milk and continue whisking and heating until the mixture becomes thick and creamy.
Add the cheese and stir until melted and you have a nice, cheesy sauce.
Drain your pasta and immediately then add to the cheese sauce & toss together.