Preheat your oven to 350°F (175°C) and prepare a baking dish by greasing it lightly.
In a blender, process the rolled oats until they reach a fine flour consistency.
In a large mixing bowl, combine the oat flour, baking powder, baking soda, garlic powder, black pepper, and salt.
In another bowl, whisk together the eggs, Greek yogurt, and olive oil until smooth.
Gradually add the wet ingredients to the dry ingredients, mixing until just combined.
Fold in the crumbled feta cheese and the chopped fresh herbs, reserving some feta and herbs for topping if desired.
Pour the batter into the prepared baking dish and spread it evenly.
Sprinkle the reserved feta and herbs on top, and add optional chili flakes or sesame seeds if using.
Bake in the preheated oven for about 30-35 minutes, or until the top is golden and a toothpick inserted in the center comes out clean.
Allow the cake to cool slightly before slicing and serving.
