01 - Preheat oven to 375°F. Lightly grease a small 1-quart baking dish with cooking spray or a small amount of olive oil.
02 - Heat 1 tablespoon olive oil in a skillet over medium heat. Add minced garlic and sauté for 30 seconds until fragrant, being careful not to brown.
03 - Add chopped spinach to the skillet. Sauté for 2-3 minutes, stirring occasionally, until spinach is completely wilted. Remove from heat and let cool slightly.
04 - In a large mixing bowl, combine crumbled feta, softened cream cheese, Greek yogurt, and half of the shredded mozzarella. Mix until mostly smooth and well combined.
05 - Fold in the cooled sautéed spinach, sliced pepperoncini, dried oregano, crushed red pepper flakes (if using), and black pepper. Stir until evenly distributed throughout the cheese mixture.
06 - Spoon the mixture into the prepared baking dish, spreading evenly. Top with remaining mozzarella cheese and drizzle with the remaining 1 tablespoon olive oil.
07 - Bake for 20-25 minutes, until the dip is bubbling around the edges and the top is lightly golden brown.
08 - Remove from oven and let rest for 5 minutes to set. Garnish with chopped fresh parsley or dill and serve with lemon wedges on the side.