Stir the pasta into the sauce and bake in a greased 2 quart dish (or an 8x8 pan works pretty well) 20-25 minutes until browned and bubbly. You can also skip baking it if you want it super creamy and just put it under the broiler to brown the top (keep an eye on it) and then serve.
The thinner the dish, the less the bake time. I used a cast iron skillet and mine was done in 25 minutes. A thicker dish like a 2 quart casserole will take 40 minutes.
To make ahead, cool the pasta and cheese sauce once they have been mixed together, cover with plastic wrap and chill until ready to bake. Up to two days. Bake until hot in the center and bubbling around the edges.