Once the butter has fully melted, add in your sliced White Onion and pinch of salt. Allow it to cook over medium-low heat until caramelized, about 30 minutes.
Cook pasta according to package directions. Meanwhile, place 2 tablespoons of butter in a large pan over medium-high heat. Once the butter has melted, add in the flour and stir until combined.
While using a whisk, slowly pour in the milk. Bring to a boil and reduce to medium heat. Simmer and stir until the sauce has thickened, about 5-6 minutes.