Hard-boil the quail eggs, peel them, and set aside.

Wash the spinach, roughly chop the leaves, and sauté them for about 10 minutes in a skillet with 1 tablespoon of oil. Season with salt. Let cool.

In a bowl, sift together the flour and baking powder. Add the Parmesan, salt, and pepper, and mix well. In another bowl, whisk together the large eggs, vegetable oil, and milk. Pour the wet ingredients into the flour mixture, stir briefly, then add the spinach.

Mix until just combined. Divide the batter evenly among the greased and floured muffin cups. Press a quail egg into the center of each muffin, pushing it well into the batter.

Bake at 350°F (180°C) for about 20–25 minutes. Let cool in the pan for a few minutes, then transfer to a wire rack.