Preheat oven to 350°F (175°C). Grease and flour a 9-inch springform pan.
In a bowl, whisk together flour, baking powder, baking soda, and salt.
In another bowl, beat eggs and sugar until pale and fluffy.
Add olive oil, milk, vanilla extract, and lemon zest to the egg mixture and mix well.
Gradually add the dry ingredients into the wet ingredients and stir until combined.
Gently fold in 1 1/2 cups of grapes.
Pour batter into the prepared pan and top with remaining grapes.
Bake for 45-50 minutes or until a toothpick inserted into the center comes out clean.
Cool completely before slicing and serving.