Preheat your oven to 350°F (180°C) and line a large baking sheet with parchment paper.
In a food processor (or smoothie blender), blend together spinach and vegetable oil until the mixture is smooth and well combined. The smoother the mixture, the more vibrant the color of the cake will be. Set this mixture aside.
4 ounce baby spinach, 3 tablespoon vegetable oil
In a mixing bowl, whisk together eggs and sugar until fluffy. Stir in vanilla extract. Then, add the spinach puree to the egg mixture and mix until fully combined.
3 large egg, ½ cup granulated white sugar, 1 teaspoon vanilla extract
In another bowl, mix together the dry ingredients, then gradually add them to the wet mixture, stirring until just combined.
1 teaspoon baking powder, ¾ cup + 1 tablespoon all purpose flour, 1 pinch of salt, 1 teaspoon cornstarch
Pour the batter onto the prepared baking sheet and bake for 12-15 minutes, or until the cake is set and appears pale-ish green. Remove the cake from the baking sheet and allow it to cool.
Use a 3-inch egg-shaped cookie cutter to cut out 12 egg shapes from the cooled cake.
With the remaining batter, crumble it and set it aside for to enjoy later.