Add pasta, broth, mustard, and garlic powder, to the inner pot of the pressure cooker. Stir to combine.
Close the lid and set to sealing. Cook on manual high pressure 3 minutes. Wait for it to come to pressure. (It took my Instant Pot 5 minutes to reach pressure.) Using an oven mitt or towel, do a quick release and carefully open the lid so the steam escapes away from you.
While hot, add the warm milk and shredded cheeses. Stir continuously until the cheese melts into a smooth creamy sauce. If there’s excessive liquid, saute the mixture for 3-5 minutes on normal heat.
Stir in the spinach. Let sit for 5 minutes to thicken. Taste and add cracked black pepper to taste and salt if needed. Enjoy warm with a salad if you’d like even more veggies.
Notes
Allow time for the cheese sauce to thicken
If there’s excessive liquid, saute the cooked pasta and cheese mixture for 3-5 minutes on normal heat. Do not overcook.The key to a thick creamy sauce is time - allow the mac and cheese to sit about 5 minutes before diving in.
Trying this recipe without an Instant Pot?
You can use this recipe for any electric pressure cooker. And I do recommend this one-pot method since it's quick and easy!