Turn your Instant Pot on Sautee and melt butter in the liner.
Add flour to the butter and wisk until smooth.
Add the chicken broth, onion, broccoli, garlic, salt and pepper to the Instant Pot.
Cook on Manual (or pressure cook) HIGH for 2 minutes. Allow for a 2 minute Natural Pressure Release before releasing the pressure manually.
Carefully remove lid and stir in the heavy cream and cheeses.
Replace lid for 2 minutes to allow the cheese to melt.
Remove lid, give a quick stir, and serve hot!