To the Instant Pot, add pasta, butter, garlic, dijon mustard, nutmeg, salt, and pepper. Followed by the stock.
Give the ingredients a quick stir and try to get all of the pasta covered in liquid (add a little bit of water if necessary).
Secure the lid and set the vent to SEALING. Select the PRESSURE COOK/MANUAL setting and set the cooking time for 5 minutes at high pressure. The Instant Pot will take around 5 minutes to come to pressure and start cooking. When the cooking program ends, quickly release the steam.
Carefully remove the lid, give the pasta a stir and check the amount of the liquid, if there's too much liquid left then you can discard a small amount.
Stir in the cream and cheese, and add the broccoli florets. Keep stirring until the cheese has completely melted and the sauce is creamy. Adjust the seasonings to your preference.
Cover the lid, and let the broccoli "steam" and soften for a few minutes. Serve warm.
Use any type of short pasta shape such as macaroni, rotini, fusilli, or pasta shells.
The most popular choice of cheese is cheddar, don’t use extra sharp or aged cheddar. Go for medium or sharp cheddar, other great choices are Monterey Jack, Mozzarella, Fontina, or Colby.
Substitute heavy cream with half and half if you prefer.
For a silky smooth rich sauce, get a block of cheese instead of the pre-grated stuff. The store grated cheese doesn’t melt very well as it contains anti-caking agents.
When reheating mac and cheese, add a splash of water as the sauce will be too thick.
The recommended portion size of pasta per person is 2 ounces (60 grams).