1. 1. Prepare the spinach: If your frozen spinach isn’t already thawed, place it in a microwave-safe bowl and microwave on high for 2-3 minutes, or until defrosted. Once thawed, place the spinach in a clean kitchen towel or several layers of paper towels and squeeze out as much excess water as possible. This step is crucial to prevent a watery dip. You should see a significant amount of liquid come out.

2. 2. Chop the artichoke hearts: Drain the canned artichoke hearts well and give them a rough chop. You can leave them a bit chunkier for more texture or chop them finely if you prefer a smoother dip.

3. 3. Combine the wet ingredients: In a medium-sized mixing bowl, add the plain Greek yogurt and mayonnaise. Stir them together until they are well combined and smooth.

4. 4. Add the seasonings: Mince your garlic cloves and add them to the yogurt mixture. Stir in the onion powder, salt, black pepper, and optional red pepper flakes. Mix thoroughly to ensure the seasonings are evenly distributed.

5. 5. Fold in the main ingredients: Add the squeezed dry spinach and chopped artichoke hearts to the bowl with the yogurt mixture.

6. 6. Stir in the Parmesan cheese: Add 1/2 cup of grated Parmesan cheese to the bowl.

7. 7. Mix thoroughly: Using a spatula or large spoon, gently fold all the ingredients together until everything is uniformly combined. Make sure there are no pockets of unmixed yogurt or mayonnaise. The dip should look thick and creamy, with visible flecks of spinach and artichoke.

8. 8. Chill and serve: Cover the bowl with plastic wrap and refrigerate for at least 30 minutes to allow the flavors to meld. Before serving, sprinkle with a little extra grated Parmesan cheese if desired.