In a large bowl, whisk together flour, sugar, lemon zest, baking powder, salt, and baking soda.
Add egg, egg yolks, oil, milk, and vanilla.
Whisk until smooth.
Gently pour or ladle batter over lemon slices in prepared pan.
Bake for 30 minutes, or until cake tests done.
Cool in pan before turning out.
Remove parchment paper and serve.