Make Spinach Dip in 35 minutes for a warm, cheesy appetizer that’s perfect for sharing.
Preheat the oven to 400°F and prepare a 1-quart baking dish by spraying it lightly with non-stick cooking spray; set the dish aside to stay ready. Treat this as your first active step—get the vessel greased and waiting so the mixture can be transferred cleanly when it's ready.
In a medium mixing bowl add the softened cream cheese and the sour cream, then beat them together with a hand mixer until the mixture is completely smooth and glossy. Scrape the sides with a spatula so there are no lumps; the texture should be silky and homogenous before you add the seasonings and cheeses.
Add the minced garlic, onion powder, shredded mozzarella, grated Parmesan, kosher salt and black pepper to the smooth cream base. Fold in the thoroughly thawed and well-drained spinach until the green ribbons are evenly distributed and the mixture looks cohesive—creamy white and green with flecks of cheese. Transfer and spread the dip evenly into the prepared rustic oval baking dish so the top is smooth and level, ready for the oven.

Bake the filled dish for 15–20 minutes, or until the surface is bubbling and the top is gently golden and slightly crisp. Let it rest briefly, then scoop to reveal the velvety, molten interior and serve warm alongside sliced bread, a toasted baguette, or crackers for dipping.
