Grease and flour the cake pans very well then line the bottoms with baking paper. These cakes are quite delicate so I highly recommend taking the extra step of lining at least the bottoms with the baking paper to prevent the cakes from sticking. Set aside. Preheat the oven to 160C/325F.
In a large bowl, add the flour, baking powder, baking soda, cornstarch/cornflour and salt and whisk until very well combined. Set aside.
In a large mixing bowl, whisk butter until creamy then add in the sugar gradually. Once combined, add in 2 tablespoons of the oil and whisk until mixture is paled in colour and fluffy, about 3 to 4 minutes (click here for references).
Add in the remaining 2 tablespoons of oil then the eggs one at a time whisking well in between each addition. Add in vanilla extract and whisk to combine.
Alternate in the dry ingredients with the milk and sour cream in alternating batches starting and ending with the dry ingredients. Make sure you whisk the last addition of dry ingredients until *just* combined taking care not to over mix. Batter is slightly thick.
Divide batter between cake pans and bake for about 20 to 25 minutes until baked through and a toothpick or knife comes out clean or with a few moist crumbs. Allow the cakes to cool in the pans for a minimum of 40 to 45 minutes before removing onto a wire rack to cool completely.
Allow to cool completely before filling and frosting. Store cake in airtight container for up to 5 days.
*All purpose flour and cornstarch can be replaced with 2 1/2 cups + 2 tablespoons cake flour.
**Add in 1/4 cup (50gms) extra butter instead of the oil for a slightly denser cake so you would use 3/4 cup (150gms) butter altogether.
** *This may seem like alot of vanilla extract but honestly it’s not. If you would like to reduce it then I don’t recommend adding less than 3 teaspoons.o
