Instant Pot Mac & Cheese with Lemony Garlic Breadcrumbs

For the mac and cheese:

• 2 tablespoons unsalted butter, divided
• 2 1/2 cups whole milk
• 1/4 cup heavy cream
• 6 ounces cream cheese, at room temperature
• 1 garlic clove
• 1 teaspoon dried mustard
• 1 tsp kosher salt
• 1/4 teaspoon freshly ground black pepper
• 1/8 teaspoon cayenne pepper
• Pinch of freshly grated nutmeg
• 12 ounces dried pasta
• 8 ounces sharp cheddar cheese, grated

For the breadcrumbs:

• 3 tablespoons butter
• 2 garlic cloves, finely chopped
• 4 ounces (about 2 1/2) cups fresh breadcrumbs
• kosher salt
• freshly ground black pepper
• zest of 1/2 lemon

Chopped parsley, for serving