In a large sauce pan melt the butter and cook the onion until translucent. Add the garlic and cook an extra minute.
4 Tablespoons unsalted butter, ½ cup minced white onion, 1 Tablespoon minced garlic
While the onions are cooking, heat a large pan of water. When it begins to boil, add the spinach and blanch for one minute. Remove from the water and add to an ice water bath. Drain and squeeze dry.
16 ounce bag fresh spinach
Add the heavy cream, mozzarella, cream cheese and parmesan to the onions and cook till warmed and bubbly.
1 cup heavy cream, 1 cup shredded mozzarella cheese, 4 ounces cream cheese, ½ cup shredded parmesan cheese
Chop the spinach and add to the creamy mixture. Cook for 2 more minutes. Sprinkle in the seasonings and stir to incorporate.
½ teaspoon pepper, ½ teaspoon salt, ¼ teaspoon nutmeg