Creamy Instant Pot Mac and Cheese

Ingredients (9)

• 1 pound macaroni pasta such as shells or cavatappi
• 4 cups water
• 4 tablespoons butter
• 1 teaspoon kosher salt
• 1 teaspoon ground mustard
• 1/2 teaspoon garlic salt optional
• 1 5- ounce can evaporated milk
• 4 cups shredded medium or sharp cheddar cheese
• 2 cups soft white cheese such as gouda Swiss, fontina, or provolone