Instant Pot Sausage and Potato Casserole

Name: Instant Pot Sausage and Potato Casserole
Cuisine: American
Ingredients: 1 1/2 lb (700g) fresh diced potatoes; 1 lb (450g) kielbasa sausage, cut into small pieces; 1 small onion, diced; 2 or 3 garlic cloves, minced, optional; 2 1/2 cups shredded cheddar cheese; 1 1/2 to 2 cups (500ml) chicken or vegetable stock; 1/2 cup (125ml) milk; 1/4 cup (60ml) heavy whipping cream; 1/2 tablespoon unsalted butter, diced; 1 teaspoon Italian seasoning, optional; 1/2 teaspoon Cayenne pepper, optional; Salt and pepper, to taste