Begin by preheating your oven to 325°F. Prepare three 8-inch round cake pans by generously spraying them with non-stick baking spray or greasing and flouring them. In a mixing bowl, combine the oil and butter and beat on high speed for 2 minutes. Gradually add the sugar while continuing to beat on high speed for another 4-5 minutes, until the mixture becomes very pale yellow and fluffy. Next, add the eggs one at a time, beating well after each addition and scraping down the bowl sides as needed. Stir in the vanilla extract. In a separate medium bowl, sift together the cake flour, baking powder, salt, and baking soda. Reduce the mixer speed to low and add the sifted dry ingredients to the batter in two parts, mixing carefully to avoid overbeating. Finally, add the sour cream and heavy cream, scrape down the sides again, and mix just until combined. Pour the batter evenly into the prepared pans. Bake for 17 to 24 minutes, checking for doneness by inserting a toothpick into the center—it should come out nearly clean but be careful not to overbake. I recommend beginning to check at 16 minutes as ovens vary. Once baked, let the cakes rest in their pans for 10-15 minutes before inverting them onto cooling racks to cool completely.

For the Caramel Icing:

Combine the butter, evaporated milk, and sugar in a saucepan over medium-low heat, stirring until fully melted and combined. Continue cooking on medium-low heat, stirring constantly, for about 1 1/2 to 2 hours. Watch closely to prevent burning as the mixture thickens and darkens to a rich golden brown. If it’s taking too long, you can slightly increase the heat but be vigilant and stir frequently. The caramel should reach a color and thickness similar to the reference photo and video — it must coat the back of a spoon thickly. Adjust the heat as needed to avoid burning. Once the caramel has thickened properly, remove from heat and stir in the vanilla extract. Let it cool for 15-20 minutes to thicken further before using it to ice the cake. If it remains too warm and runny, refrigerate until it firms up. Optional: some prefer whipping the caramel in a stand mixer to achieve a frosting-like texture—feel free to do this if you like.

Make sure your cake layers are completely cooled before assembling. Place a small dollop of icing in the center of your cake plate or stand to secure the first layer. Position the first cake layer on top. Using an offset spatula, spread about a quarter of the caramel icing evenly over the layer, reaching to the edges. Allow the icing to set for about 5 minutes to firm slightly. Carefully place the second layer centered on top, then spread another quarter of the icing over it and let it set for another 5 minutes. Add the final cake layer, then cover the entire cake with the remaining caramel icing, spreading it evenly over the top and sides. Let the cake set for about 30 minutes before serving.