Preheat your oven to 160°C (320°F) with the fan setting on. If your oven doesn’t have a fan function, refer to note 1 for adjustments. Prepare two 8-inch cake tins by greasing them or lining them with parchment paper—I prefer using my homemade cake release for best results. In a medium bowl, sift together the flour, cornstarch, baking powder, and salt. Use a whisk or fork to mix everything thoroughly and set aside. In a large mixing bowl, combine the butter, vegetable oil, granulated sugar, and light brown sugar. With an electric mixer (either hand-held or stand mixer—see note 2), beat the mixture for about 2 minutes until it becomes light and fluffy. Add the eggs one at a time, mixing well for about 10–15 seconds after each addition. Stir in the sour cream and vanilla extract and mix until everything is fully incorporated. Set the mixer aside and complete the remaining steps by hand. Begin by folding in half of the dry ingredients with a spatula, mixing gently until just incorporated. Pour in the milk and fold it in carefully. Finally, add the remaining dry ingredients and fold again, being cautious not to overmix the batter (see note 3). Divide the batter evenly between the two prepared cake tins and bake for 28 to 30 minutes, or until a toothpick inserted in the center comes out clean. Once baked, allow the cakes to cool in their tins for 15–20 minutes, then turn them out onto a wire rack and let them cool completely before adding the caramel frosting.

In a large saucepan over medium heat, combine the butter, granulated sugar, evaporated milk, and salt. Stir continuously as the ingredients melt together and begin to simmer. Once the mixture reaches a simmer, reduce the heat to low-medium and allow the caramel to thicken slowly over the next hour. Stir the caramel every few minutes to prevent it from sticking or burning, especially as it begins to thicken—this is when it’s most delicate. When the caramel becomes thick and turns a deep golden-brown color (refer to the video if provided for visual guidance), stir in the cream and vanilla extract. Mix until smooth, then pour the caramel into a heatproof dish to cool. Let the caramel sit for about 25 minutes before using it to frost the cake. It should still be warm and slightly runny at this point, as it will continue to thicken as it cools (see note 4 if the caramel is too thick to spread).

After the cake layers have completely cooled, use a serrated knife to level the tops if needed, ensuring both layers are flat. Place the first cake layer on a serving platter or cake stand and spread a generous amount of caramel frosting over the top using an offset spatula or butter knife. Gently place the second cake layer on top, then frost the top and sides of the cake with more caramel frosting (see note 5 if your frosting seems too runny and won’t set). As the caramel begins to set, it will take on a glossy appearance. For a smooth finish, gently run a clean offset spatula or knife over the shiny caramel surface. Decorate however you like and enjoy your delicious homemade caramel cake!