Creamed Spinach Casserole

Name: Creamed Spinach Casserole
Ingredients: 3 tablespoons unsalted butter; 1 yellow onion, chopped; 4 cloves garlic, finely chopped (about 4 teaspoons); 2 5.2-ounce packages herb-and-garlic soft cheese (such as Boursin); 1 teaspoon kosher salt; 1/2 teaspoon ground black pepper; 1/4 teaspoon ground nutmeg; 2 12-ounce packages frozen chopped spinach, thawed and squeezed dry; 2 ounces Parmesan cheese, grated (about 1/2 cup), divided; 1 cup heavy cream; 16 round, buttery crackers (such as Ritz), crushed into fine crumbs