Cook the pasta in well salted water.
Pre heat your milk in the microwave for 45 seconds – just enough to take the chill out of it.
Melt butter in a sauce pan over medium heat and let it heat until it becomes foamy.
Mix in flour. Cook it for a minute while stirring constantly
Slowly add warmed milk to the butter mixture 1/4 cup at a time. Whisk it continually until combined. Season generously with salt and fresh cracked pepper.
Once all of the milk is added, cook for a few minutes while whisking it. Do not let it boil. You will feel the sauce start to thicken. It’s ready for cheese when you rub a small amount between your fingers and it feels silky.
Remove from heat and stir in cheese until it’s melted and mixed into the sauce.
Once the cheese is incorporated, use a cooked noodle to taste your sauce. If it doesn’t taste cheesy enough try adding a little more salt to bring out the flavor.
Combine the pasta and sauce, top with crispy onions, and serve.