Add 1 lb (whole box) of dry pasta, broth and 2 tablespoons butter to instant pot pan. Stir to make sure pasta is not stuck together or to the bottom of the pan.
Place lid on Instant Pot, Cook on Manual for 4 minutes. Carefully Quick Release Pressure.
To cooked noodles, add remaining butter, 1 cup of cheese, and heavy cream and mix until cheese is fully melted.
Add cheese 1 cup at a time stirring well in between additions so that cheese fully melts and incorporates in pasta