This incredibly simple stove top mac & cheese far surpasses any recipe I've tried in both flavor and texture. It is crazy rich and crazy delicious. For my family of 5, I always double the recipe and for best results, serve it immediately--as it sits the sauce will begin to thicken.
Melt the butter in a large skillet over medium-low heat. Add the onion and cook for 5 minutes, stirring occasionally until onion is soft and translucent. Stir in the oregano, salt and flour and cook for 1 minute more.
Add the half and half and pasta and bring to a boil. Cover, reduce heat to low and simmer for 15 minutes or until pasta is cooked through.
Add the cheese and stir until melted. Serve immediately.