Preheat the oven to 375°F (190°C).
Brush a standard 24-cup mini muffin tin with melted butter.
Lay one sheet of filo pastry on a clean surface and brush it lightly with melted butter. Place another sheet on top and brush with butter again. Repeat layering and brushing until you have 3 layers.
Cut the layered filo sheets into 24 squares approximately 4×4 inches each.
Gently press each filo square into the muffin tin cups, forming little cups. Repeat with remaining filo sheets and butter.
Bake the filo cups in the preheated oven for 8-10 minutes or until golden and crisp. Remove from oven and let cool slightly.
In a large mixing bowl, combine the softened cream cheese, sour cream, and mayonnaise. Mix until smooth.
Add the chopped spinach, chopped artichoke hearts, shredded mozzarella, grated Parmesan, minced garlic, salt, and black pepper. Stir until all ingredients are well combined.
Spoon about 1 tablespoon of the spinach and artichoke mixture into each filo cup, filling them generously.
Return the filled filo cups to the oven and bake for an additional 10 minutes, or until the filling is hot and bubbly.
Remove from the oven and allow to cool for 5 minutes before serving.