Preheat your oven to 170°C fan setting.
Take 2 round baking tins (about 10 inch diameter) and line them with parchment paper.
Take your eggs and separate the egg yolks from the egg whites. Set them aside.
Place your softened butter in a mixer and beat for 1 minute until nice and fluffy.
Add in the vegetable oil and beat for another minute or so.
Add in the sugar half at a time, and blend together. The mixture should become slightly lighter in colour and airy.
Add in the egg yolks and mix together.
Add in the milk, vanilla extract, lemon juice and yoghurt to the mixer. Blend for a minute or so to combine all the wet ingredients.
Then start adding in the dry ingredients to the mixer. Start with the plain flour and then add the corn flour, baking powder, baking soda and salt. Beat until just combined.
Empty the batter into a large mixing bowl.
Take the egg whites that you set aside earlier and beat them until they form stiff peaks. Add them to the bowl with the batter and stir very gently until they are just mixed in.
Take your washed raspberries and sprinkle 1 tablespoon of flour over them until coated.
Gently add them to the bowl of batter as well, stirring until evenly distributed.
Pour the mixture evenly into each of your prepared round cake tins and place them in the middle shelf of the oven.
Bake for about 35-40 minutes, or until a knife comes out clean.
Remove your cake layers from the oven and allow them to cool completely in the tins. It’s very important that it does cool completely to stop the cake from sticking and crumbling.