Kosher salt and freshly ground black pepper, to taste
¼cupbeef broth
1tablespoonred wine, optional
4ouncescream cheese, at room temperature
¼cupsour cream
3tablespoonsmayonnaise
1cupshredded mozzarella cheese, divided
2tablespoonsfreshly grated Parmesan
2tablespoonschopped fresh parsley leaves
Instructions
Preheat oven to 350 degrees F. Lightly oil a 9-inch baking dish or coat with nonstick spray.
Melt butter in a large skillet over medium high heat. Add onions, garlic and thyme; season with salt and pepper, to taste. Cook, stirring occasionally, until the onions are very soft and caramelized, about 25 minutes.
Stir in beef broth and red wine, if using. Bring to a simmer; remove from heat and stir in cream cheese, sour cream, mayonnaise, 1/2 cup mozzarella and Parmesan.
Spread mixture into the prepared baking dish; sprinkle with remaining 1/2 cup mozzarella. Place into oven and bake until bubbly and golden, about 10-12 minutes.
Serve immediately, garnished with parsley, if desired.