Step 1Heat the oven to 350 degrees. Grease muffin tins.
Step 2In the bowl of a stand mixer fitted with the whisk attachment, beat the eggs and sugar together until pale and thick, about 4 minutes.
Step 3In a separate bowl, combine the milk, olive oil and citrus zest. With the mixer running, slowly add to the egg mixture, scraping the bowl down once while mixing to make sure all of the ingredients are incorporated.
Step 4In a separate bowl, whisk together the flour, baking powder, baking soda and salt. Over low speed, slowly add the dry ingredients to the egg mixture, scraping down the bowl once again while mixing to make sure the dry ingredients are fully incorporated.
Step 5Spoon the batter into the lightly greased muffin tins, filling each cup about three-fourths of the way full. Bake the cakes until a toothpick inserted in the center comes out clean, 18 to 24 minutes, rotating the muffin tins halfway through baking for even heating.
Step 6Cool the cakes completely, then dust lightly with powdered sugar and sprinkle over extra citrus zest before serving.