Step 1: Thaw the frozen spinach and squeeze out ALL excess water using a clean kitchen towel or paper towels. Drain the canned artichoke hearts and roughly chop them.
Step 2: In a medium bowl, combine the softened cream cheese, mayonnaise, and sour cream. Stir until the mixture is smooth and creamy.
Step 3: Add the drained spinach, chopped artichoke hearts, minced garlic, onion powder, grated Parmesan cheese, salt, and pepper to the cream cheese mixture. Stir everything well until all ingredients are evenly combined.
Step 4: Slice your bagels in half horizontally. For a crispier base, you can lightly toast them in a toaster or oven for a few minutes before the next step.
Step 5: Generously spread the spinach-artichoke mixture onto each bagel half. Top each bagel half with a good sprinkle of shredded mozzarella cheese.
Step 6: Place the bagel halves on a baking sheet. Bake in a preheated oven at 375°F (190°C) for 10-15 minutes, or until the cheese is melted, bubbly, and lightly golden brown. Serve warm and enjoy!