01 - Preheat the oven to 400°F. Lightly grease an 8-inch baking dish with olive oil or cooking spray.
02 - In a medium bowl, mash the feta cheese, cream cheese, and Greek yogurt together until mostly smooth. Small feta crumbles are acceptable for texture.
03 - Add the chopped spinach, minced garlic, green onions, sliced pepperoncini, olive oil, dried oregano, black pepper, and red pepper flakes. Mix thoroughly until evenly distributed.
04 - Spoon the mixture into the prepared baking dish and spread into an even layer using the back of a spoon.
05 - Bake for 20 to 25 minutes until the dip is hot and bubbly with golden-brown spots appearing on the surface.
06 - Remove from the oven and let cool for 5 minutes. Top with fresh chopped dill or parsley and lemon zest if desired. Serve warm with pita chips, baguette slices, or fresh vegetables.