I followed the recipe below, but I browned a pound of smoked sausage pieces on Sauté first before adding the pasta and water and stuff, then when the mac and cheese was all done, I stirred in some thawed green peas. (And I did not add the bread crumb topping...this time.)
Oh, and it gets a little lumpy and grainy overnight in the fridge, but it smooths right back out if you stir in a couple/few tablespoons of half-n-half as you reheat.
Instant Pot Mac and Cheese
(Source: adapted from Dad Cooks Dinner)
1 pound dried elbow macaroni (I used shells)
2 tablespoons butter
1 tablespoon yellow mustard (I used 1 teaspoon Dijon plus 2 teaspoons yellow)
1 teaspoon hot pepper sauce
1 tablespoon kosher salt (I used about 2 teaspoons of Cajun seasoning)
4 cups water
1 (12 ounce) can evaporated milk
16 ounces shredded extra-sharp cheddar cheese
6 ounces shredded Parmigiano cheese
Bread Crumb Topping (optional)
1 cup panko bread crumbs
Pressure cook the pasta and spices: Stir the macaroni, butter, mustard, hot pepper sauce, salt, and four cups water in the pressure cooker pot. Lock the lid on the pressure cooker and bring the cooker up to high pressure. Cook on high pressure for four minutes, then quick release the pressure and remove the lid.
Stir in the evaporated milk and cheese: Turn the heat under the pot down to low (or turn the electric pressure cooker to simmer), and stir in the evaporated milk. Test a piece of pasta by taking a bite--it should be al dente, but cooked through. If the pasta is still tough in the middle, simmer it for a few minutes, until it is tender. Stir in the cheese one handful at a time, stirring constantly and waiting for the current handful to melt before adding the next handful.
Top with breadcrumbs and broil: Optional step, if you like a toasted bread crumb topping: Pour the macaroni into a 3 quart broiler-safe dish, patting it down to level out the surface. Sprinkle the panko over the macaroni and cheese in an even layer. Broil the macaroni and cheese on high until the bread crumbs are toasted, about 5 minutes. Check the bread crumbs often--they go from pale brown to burnt in a flash.