Fully thaw the frozen chopped spinach (leave in refrigerator overnight or microwave briefly). Once thawed, place spinach in a clean kitchen towel or several layers of paper towels and squeeze out as much liquid as possible until almost dry — about 1/2 cup of expelled water.

Prepare artichokes

Drain canned artichoke hearts well, then roughly chop into 1/2-inch pieces. Pat lightly with paper towel to remove excess moisture.

Make the dip

In a large mixing bowl, soften the cream cheese by stirring or beating with a wooden spoon or hand mixer until smooth.

Add sour cream, mayonnaise, grated parmesan (reserve 2 tablespoons for topping), and shredded mozzarella to the bowl. Mix until combined and creamy.

Stir in the well-drained spinach, chopped artichoke hearts, minced garlic, chopped jalapeño or chilis, lemon juice, kosher salt, black pepper, and red pepper flakes (if using). Fold everything together until evenly distributed. Taste and adjust seasoning (add up to 1/4 tsp more salt if needed).

Bake

Transfer the mixture into the prepared skillet or baking dish, spreading it into an even layer.

Sprinkle the reserved parmesan and the extra parmesan (from the Topping section) evenly over the top. Drizzle the teaspoon of olive oil lightly over the cheese to promote browning.

Bake in the preheated oven for 20-25 minutes, until the edges are bubbly and the top is golden brown. If you prefer a more browned top, place under the broiler for 1-2 minutes while watching closely to avoid burning.

Finish and serve

Remove from oven and let rest for 5 minutes to thicken slightly. Sprinkle chopped fresh parsley over the top if using.

Serve warm with tortilla chips and/or sliced baguette or crostini. Store any leftovers in an airtight container in the refrigerator for up to 3 days; reheat in a 350°F (175°C) oven for 10–12 minutes or until warmed through.