Place paper cupcake liners into muffin tins and set aside.
In a medium mixing bowl whisk together the flour, baking powder and salt.
Place the egg yolks and 10tbsp of the sugar into the bowl of your stand mixer and whisk on high for 1.5-2 minutes (until the mixture becomes pale yellow and 'ribbons' when lifted from the bowl.)
Add the water, vegetable oil and vanilla and whisk to combine.
Add the dry goods and whisk just to combine.
Transfer the batter to a mixing bowl while you whisk the egg whites.
Place the egg whites and cream of tartar into a CLEAN bowl and whisk on high using your whisk attachment, waiting for it to become foamy.
Decrease the speed to low and gradually add the remaining 2tbsp of sugar.
Increase speed to high and continue whisking until stiff peaks form, approximately 2-3 minutes.
Transfer 1/3 of the egg whites to the batter and whisk until well combined.
Add the remaining egg whites and fold in gently.
Transfer batter into prepared muffin tins, evenly dividing the batter between the cups.
Place muffin tins on the middle rack of the oven.
Bake for 30 minutes, until a toothpick comes out clean. Remove from the oven to a cooling rack and allow to cool before frosting.