Let’s build this candy bar dream cake, layer by layer:

1. Make the Chocolate Cake Layers:

Preheat your oven to 360°F (180°C). Grease and line two 8-inch round cake tins with parchment paper.

In a large mixing bowl (preferably stand mixer), sift together the plain flour, cocoa powder, baking powder, and baking soda. Add the caster/granulated sugar, brown sugar, and salt. Whisk briefly to combine.

In a separate medium bowl, whisk together the buttermilk, vegetable oil, vanilla extract, and room temperature eggs.

Add the wet ingredients to the dry ingredients in the mixer bowl. Mix on low speed, then medium, until just combined.

Slowly pour in the hot water (or hot coffee) while the mixer is on low speed. Mix until all ingredients are incorporated and the batter is smooth (it will be thin). Scrape the bowl.

Divide the batter evenly between the two prepared cake tins.

Bake for approximately 30 minutes, or until a skewer inserted into the center comes out clean.

Let the cakes cool in their tins for 10 minutes, then gently remove them and let them cool completely on wire racks.

2. Make the Salted Caramel Frosting:

While the cakes cool, make the frosting. Add the softened butter to a large mixing bowl (or stand mixer bowl). Beat with an electric mixer until smooth and creamy.

Gradually add the sifted powdered or icing sugar, beating on low speed until incorporated, then increasing speed until smooth. Scrape the bowl.

Add the ½ cup of salted caramel sauce. Continue to beat on medium-high speed until the frosting is smooth, creamy, and well combined. If it seems too thin, add a bit more sifted powdered sugar; if too thick, add a tiny splash of milk or cream (not listed, but a common adjustment).

3. Assemble the Cake:

Once the cake layers are completely cool, level the tops using a large serrated knife if they domed during baking.

Place the first cake layer on your serving plate or cake stand.

Spread about half of the caramel frosting evenly over the top of the cake layer.

Sprinkle generously with about half of the crushed shortbread cookies.

Sprinkle evenly with the chopped Twix bars (use all 6 chopped bars here between the layers).

Place the second chocolate cake layer on top.

Frost the top and sides of the entire cake with the remaining half of the caramel frosting. Aim for a smooth or slightly rustic finish.

4. Decorate:

Drizzle extra salted caramel sauce generously over the top of the cake, allowing it to drip down the sides.

Garnish the top with additional chopped Twix bars or whole Mini Twix bars. You can also press more crushed shortbread cookies around the base or sprinkle on top.

5. Serve or Chill:

You can serve the cake immediately at room temperature, or chill it briefly (30 mins) to help set the frosting and caramel drizzle slightly.

Store leftover cake covered in the refrigerator due to the buttercream. Let slices come towards room temperature before serving for best texture. Enjoy!