In a separate bowl, whisk eggs, sugar and olive oil, until thick and well-mixed. Whisk in the vanilla extract. Add the flour mixture and pour in the milk, stirring well with a wooden spoon until just combined. Spoon batter into prepared muffin cups, filling 2/3 of the way. Bake for 18 to 20 minutes, until center springs back when gently touched or a metal skewer inserted comes out clean.