Bake it in the oven

Edit: also use real cheese, not Velveeta or something. Use a nice cheddar.

This is a very good recipe https://www.bonappetit.com/recipe/stovetop-mac-and-cheese

After that, bake it in a casserole dish/dutch oven at like 400°F for ~20m (maybe more). Keep an eye on it, bake it until it is nice and brown on top. My spouse and I also do 8oz of each cheese instead of the asymmetric amounts. Put panko breadcrumbs and parm on top before baking it to get a nice crunch.

Wouldn’t it be the same case if you just have the bedroom door open? Like if just the door is open with no windows open.