Begin by preheating your oven to 180°C (350°F). Grease and line two 8-inch cake tins to prepare them for baking.

In a large mixing bowl, combine the softened butter, vegetable oil, light brown sugar, and vanilla extract. Beat this mixture on high speed for about 5 minutes until it becomes light and fluffy. If you're mixing by hand, whisk vigorously for as long as possible to incorporate plenty of air.

Add two of the eggs and whisk them in thoroughly. Then add the remaining two eggs and whisk again until fully combined.

Next, add the self-raising flour and the warm milk mixed with instant coffee. Whisk everything together just until you have a smooth, even batter—do not overmix.

Divide the batter evenly between the prepared cake tins, spread it out, and bake in your preheated oven for 40–45 minutes. The cakes are done when a toothpick inserted into the center comes out clean.

While the cakes are baking, prepare the milk mixture.

In a small saucepan, combine the whole milk, instant coffee, and light brown sugar. Place the saucepan over medium heat and stir gently until the coffee has completely dissolved. There's no need to bring it to a boil—you just want to dissolve the coffee granules. Alternatively, you can do this step in the microwave.

Set the milk mixture aside and let it cool. Once the cakes are out of the oven and still warm, pour the milk mixture over the tops of both cakes. Allow the cakes to absorb the liquid fully and cool completely in their tins for a few hours.

To make the caramel, add about one-third of the granulated sugar to a saucepan and place it over medium heat. Stir constantly until the sugar begins to melt. Once it starts melting, add another third of the sugar and continue stirring. After that melts, add the final third. Keep stirring as the sugar melts and slowly turns a deep amber color. Be sure not to increase the heat—slow melting helps avoid burning.

Once all the sugar has melted and the caramel is a rich amber shade, remove the pan from heat. Whisk in the room-temperature butter until fully incorporated. Then slowly pour in the warmed cream while mixing continuously. Finally, stir in the salt.

Strain the caramel through a sieve to remove any lumps, and set it aside to cool completely.

Once your cake layers and caramel have cooled, and your batch of Swiss meringue buttercream (made using light brown sugar instead of granulated) is ready, it’s time to assemble.

Place the first cake layer onto a cake plate or board. Spread a layer of buttercream over the top, then pipe a border of buttercream around the edge to form a barrier. Spoon some of the cooled caramel into the center.

Add the second cake layer on top, aligning it carefully.

Decorate the cake however you like. For a simple yet elegant finish, frost the entire cake with buttercream, drizzle caramel around the top edges for a drip effect, pipe additional buttercream decorations on top, and sprinkle lightly with ground cinnamon.

Slice, serve, and enjoy every coffee-caramel bite!