01 - Preheat oven to 350°F. Line a 9x9-inch baking pan with parchment paper or lightly grease it.
02 - If using fresh spinach, wash, dry, and roughly chop. Sauté in a large skillet over medium heat until wilted, about 2-3 minutes. Cool slightly and squeeze out excess moisture.
03 - In the same skillet, heat 1 tablespoon olive oil and cook onion and garlic until soft and fragrant, about 3 minutes.
04 - In a large bowl, whisk together eggs and olive oil until combined. Stir in ricotta, feta, and Parmesan cheeses.
05 - Add cooked spinach, sautéed onion and garlic, fresh dill, and parsley to the bowl. Stir to combine.
06 - Sift flour, baking powder, salt, and pepper into the mixture. Gently fold until just combined, avoiding overmixing.
07 - Pour the batter into the prepared pan and spread evenly. Bake for 30 minutes or until golden and a toothpick inserted in the center comes out clean.
08 - Allow to cool in the pan for 10 minutes before slicing into bars.