Step 1

Lightly beat 1 egg in a large bowl. Mince 4 garlic cloves and grate 1/2 cup Parmesan cheese, and add both to the bowl. Add 1/3 cup breadcrumbs, 1/3 cup whole milk, 1 teaspoon kosher salt, and 1 teaspoon Italian seasoning. Remove the casings from 8 ounces Italian sausage if needed, and add the sausage and 1 pound ground beef to the bowl.

Step 2

Gently mix with your hands until well combined. Form and shape the mixture into 24 meatballs (about 2 tablespoons each), and place on a plate or baking sheet.

Step 3

Bring 2 (24-ounce) jars marinara sauce and 2 cups water to a simmer in an Instant Pot or electric pressure cooker with the Sauté function. Add the meatballs, stacking them but avoiding pressing them into each other. Turn off the saute function.

Step 4

Lock the lid on and make sure the pressure valve is set to seal. Set to cook on HIGH pressure for 8 minutes. It will take about 10 minutes to come up to pressure. When the cook time is up, let the pressure naturally release for 5 minutes. Quick release the remaining pressure, and serve the meatballs as desired.