In a medium bowl, whisk together the 2 egg yolks, sugar, milk, oil and vanilla extract.
Add in the flour, baking powder and mix with a spatula until just combined. (Don't overmix). Set aside.
Add the 3 room temperature egg whites into a clean stand mixer bowl fitted with a whisk attachment.
Whip the egg whites, first starting on low speed and gradually increasing.
When until bubbles appear, add in cream of tartar (or lemon juice) and gradually add in the granulated sugar.
Continue whipping the egg whites until it reaches stiff peaks. (When the whisk is pulled out, the meringue sticks straight up, or you can turn the bowl upside down and nothing will drip).
Working in 3rds, with a spatula, fold in ⅓rd of the egg white mixture into the egg yolk mixture to lighten.
Continue folding in the remaining egg white mixture into the egg yolk mixture until homogenous, but be careful not to overmix.