Preheat the Oven: Position a rack in the upper third of the oven and preheat to 400 degrees F.
Prepare the Baking Dish: Butter an 8.5-inch round dish.
Cheese Mixture: Combine ¼ cup Parmesan cheese and ¼ cup Mozzarella cheese in a small bowl and set aside for later.
Cook the Onion Mixture: In a large 12-inch sauté pan, heat the oil and butter over medium heat. Add the chopped onion, salt, paprika, sugar, ground black pepper, and cayenne pepper.Sauté the mixture for about 10 minutes until the onions start to soften and become translucent. Reduce the heat to medium-low and continue sautéing for an additional 5 to 10 minutes, or until the onions are browned and caramelized. Add the minced garlic and cook for another 1 to 2 minutes until it becomes fragrant. Remove the pan from heat and allow the mixture to cool.
Combine with Cream Cheese Mixture: In a large bowl, mix cream cheese, sour cream, mayonnaise, ¾ cup of Monterey jack cheese, and ½ cup of Parmesan with the cooled onion mixture. Mix well and adjust seasoning if necessary.
Add the Spinach and Artichokes: Lightly squeeze the liquid out of the spinach and add to the large bowl. Drain and blot dry the artichokes with a paper towel, chop them roughly, and add to the large bowl. Stir until well combined.
Bake the Dip: Transfer the mixture to the prepared baking dish. Top with the reserved Parmesan and Mozzarella cheese mixture. Bake until the edges are browned and bubbly, about 20 to 25 minutes.
Serve Warm: Serve the Spinach and Artichoke Dip warm with crackers, chips, or toasted bread.
📌Camila's Tip: To effectively dry spinach, place thawed spinach in a clean kitchen towel over a bowl or sink and twist firmly to extract all the moisture. For fresh spinach, sauté it in batches until wilted. To swiftly soften cream cheese, microwave it in 15-second increments until it becomes soft, but be careful not to overheat.