Preparation

• Dice the onion, mince the garlic, and roughly chop the spinach, then crumble the feta cheese.
• Heat olive oil in an 8-inch oven-safe, non-stick skillet over medium heat and sauté the diced onion until softened for 3-4 minutes.
• Add the minced garlic to the skillet and cook for another minute until fragrant, then stir in the chopped spinach and cook until wilted (2-3 minutes), seasoning with salt and pepper.
• In a medium bowl, whisk together eggs, milk (if using), salt, and pepper until combined, then stir in half of the crumbled feta cheese.
• Pour the egg mixture evenly over the cooked vegetables in the skillet and gently spread the remaining feta cheese over the top.
• Cook on the stovetop over medium-low heat for 5-7 minutes, until the edges of the frittata begin to set.
• Transfer the skillet to a preheated oven at 350°F (175°C) and bake for 10-15 minutes, or until the center is set; alternatively, cover and cook on the stovetop over low heat.
• Remove from the oven, cool for a few minutes, then slide onto a cutting board, garnish with fresh parsley or chives if desired, slice into wedges, and serve immediately.