Preheat oven to 375 degrees F. In a food processor, add artichoke hearts, onion, garlic and process until finely chopped. Transfer to a medium bowl.
Add spinach, Parmesan cheese, mozzarella cheese, yogurt, mayo, red pepper flakes, salt and pepper.
Stir until well combined and transfer to a medium sized baking dish.
Bake for 15 minutes or until hot and cheese has melted. Don't over bake because yogurt will start separating.
Serve hot. Our favorite dippers include Que Pasa tortilla chips, celery and carrot sticks, thickly sliced cucumbers, whole grain crackers like Mary's Gone and Triscuits.
Notes
Store and reheat: Refrigerate leftovers in an airtight container for up to 5 days. Reheat in a microwave (best) or bake at 350 until warmed through. Not recommended to freeze.
To serve warm at a party: You can serve it in a crockpot on the Keep Warm function.