Prep: Preheat oven to 350°F. Line a 12x17" baking tray with parchment paper on the bottom only and set aside.
Separate eggs: Separate the egg whites and egg yolks into two separate large mixing bowls. Set the bowl of egg yolks aside.
Beat egg whites: To the egg whites, add cream of tartar. Use an electric hand mixer fitted with a whisk attachment to beat the egg whites until they become frothy like cappuccino foam.
Add sugar: Sprinkle in 100g of sugar, one spoonful at a time, mixing well in between each addition. After all the sugar has been added, add 1-2 drops of pink gel food colouring and continue beating the egg whites until they become stiff peaks. Set aside.
Mix egg yolk mixture: To the egg yolks, add the remaining 50g of sugar and use the same hand mixer to mix until combined. Add milk, oil, and vanilla extract. Mix again until combined.
Sift in dry ingredients: Use a fine mesh sieve to sift the flour and baking powder into the egg yolk mixture. Mix on low speed until combined and smooth.
Fold meringue into egg yolk mixture: Add ⅓ of the meringue to the egg yolk mixture. Use a silicone spatula to gently fold them together until just combined to create a looser consistency. Add the rest of the meringue and fold until no streaks remain and the batter is fluffy and airy. Be sure to scrape the bottom of the bowl where the egg yolk batter tends to settle.
Fill pan: Pour the batter into your lined baking tray. Use an offset spatula to spread the batter into the corners of the tray and smooth it into a flat, even layer.
Bake: Bake for 12-13 minutes or until the edges of the cake are lightly golden brown.
Release the cake sheet: Let the cake cool for just a few minutes before immediately running an offset spatula around the edges of the cake to release the sides from the pan. Flip the cake out of the pan onto a wire rack and peel the parchment paper off. Place a new sheet of parchment paper on top and flip the cake sheet back onto the parchment so that the side that was originally on top is back on top.
Roll up cake sheet: Use a knife to cut off the brown edges on the two short ends of the cake sheet. Starting at one of the short ends, roll up the cake sheet with the parchment paper and set aside to let it cool completely resting in this rolled-up log shape.