Thaw the frozen chopped spinach completely, then place it in a clean kitchen towel or several layers of paper towel and squeeze out as much liquid as possible. Finely chop if large pieces remain.

Drain the canned artichoke hearts well and chop them into roughly 1/2-inch pieces.

Make the Dip

Combine base ingredients

In a large mixing bowl, add the softened cream cheese, sour cream, and mayonnaise. Beat or whisk until smooth and fully combined.

Add cheeses and aromatics

Stir in the shredded mozzarella and 3/4 cup of the grated Parmesan, the minced garlic, lemon juice, kosher salt, black pepper, and red pepper flakes. Mix until evenly distributed.

Fold in spinach and artichokes

Add the well-drained chopped spinach and chopped artichoke hearts to the bowl. Fold gently until everything is evenly incorporated.

Bake

Transfer the mixture to the prepared baking dish and smooth the top. Sprinkle the remaining 1/4 cup grated Parmesan evenly over the surface.

Bake in the preheated oven for 20–25 minutes, until the edges are bubbly and the top is lightly golden.

If you prefer a more browned top, place the dish under the broiler for 1–2 minutes, watching carefully to avoid burning.

Finish & Serve

Remove the dip from the oven and let it rest for 5 minutes. Drizzle the optional teaspoon of olive oil over the top and scatter the extra grated Parmesan and chopped parsley for garnish.

Serve warm with pita chips or toasted baguette slices alongside. Leftovers can be refrigerated in an airtight container for up to 3 days and reheated in a 350°F (175°C) oven until warmed through.