Cut the apple into small chunks, set aside.
Preheat your oven to 175 C (350 F).
Add the caster sugar, brown sugar, eggs, softened butter and oil to a bowl. Whisk until incorporated and slightly lighter in color, for about 1 minute.
Add the milk, lemon juice and lemon zest and whisk until smooth.
Add the flour, oats, cinnamon and baking soda and whisk until just mixed.
Add in the chopped apples and fold until mixed.
Pour into a 20x20 cm baking dish (bottom lined with parchment paper) and bake for 30 minutes or until done.
To make the sticky apple caramel, chop the apples into very small cubes, and add that to a large pot alongside the caster sugar, brown sugar, butter and apples and cook on high heat for about 8-10 minutes or until the caramel is thick and the apples are translucent.
Add the heavy cream and cook the caramel on medium-low for a couple of minutes until thickened.
Add the vanilla and salt and mix.
Prick the cake with a fork, add the warm caramel.
Wait about 15 minutes before serving the cake to give the caramel a chance to set a little bit.
To make the runny whipped cream, add heavy cream and vanilla to a bowl, whisk for about a minute max. It’s ready when it coats the back of a spoon.
Serve the cake warm.
