01 - Preheat oven to 400°F. Lightly grease an 8-inch baking dish with cooking spray or olive oil.
02 - In medium bowl, mash feta cheese, cream cheese, and Greek yogurt until mostly smooth. Small feta crumbles may remain for texture.
03 - Add chopped spinach, minced garlic, green onions, sliced pepperoncini, olive oil, dried oregano, black pepper, and red pepper flakes. Stir until thoroughly incorporated.
04 - Spread mixture evenly into prepared baking dish, smoothing surface with spatula.
05 - Bake for 20 to 25 minutes until dip is hot, bubbly, and develops golden brown spots across surface.
06 - Remove from oven and let cool for 5 minutes. Top with fresh dill or parsley and lemon zest if desired. Serve warm with pita chips, baguette slices, or fresh vegetables.