Preheat your oven to 180°C (350°F). Line a muffin tin with paper liners or lightly grease it.
In a large mixing bowl, whisk together the flour, baking powder, and salt until evenly combined. This creates a light, airy base for the muffins.
In a separate bowl, crack in the eggs and beat them with a whisk until smooth and slightly frothy. This helps incorporate air for a fluffy crumb.
Add the olive oil and milk to the beaten eggs, whisking gently until the mixture is uniform and slightly bubbly. This mixture will add moisture and richness to the batter.
Finely chop the fresh spinach and wilt it lightly in a hot pan, then fold it into the wet mixture. This ensures the greens distribute evenly and add a tender, earthy flavor.
Gently crumble the feta cheese and fold it into the batter, distributing it evenly so pockets of salty, creamy feta form during baking.
Pour the wet ingredients into the bowl with the dry ingredients, then fold gently with a spatula until just combined. Avoid overmixing to keep the muffins light and fluffy.
Spoon the batter into the prepared muffin tin, filling each cup about three-quarters full. Use the back of the spoon to smooth the tops for a nice, rounded shape.
Bake in the preheated oven for 20-25 minutes, until the muffins are golden brown on top and a toothpick inserted into the center comes out clean. The aroma of baking spinach and feta will fill your kitchen.
Remove the muffins from the oven and let them cool in the tin for about 5 minutes. Then transfer them to a wire rack to cool completely or enjoy warm—these muffins hold their shape beautifully.
Serve the muffins warm or at room temperature. They are perfect for packing in a bag for busy mornings or storing in an airtight container for up to 3 days.
