¼cup (60 ml)Lyle's golden syrup (or light corn syrup)
4tbsp (56 g)butter
1can (14 ounces or 394 g)sweetened condensed milk
pinchof sea salt
½cup (120 ml)heavy cream
3¼cups (400 g)powdered sugar
⅔cup (80 g)unsweetened cocoa powder
1⅓sticks (150 g)butter, softened
⅓cup plus 1½ tbsp (100 ml)boiling water
2ounces (60 g)melted dark chocolate
FOR THE CAKE
Preheat the oven to 350° F. Line three 8-inch round cake pans with parchment paper (or butter and flour). Spray the parchment and sides of cake pans with nonstick spray.
In a medium bowl, add flour, cocoa powder, baking powder, baking soda, and salt and whisk to combine. Set aside.
In the bowl of a stand mixer, combine eggs, milk, oil, and vanilla. Pour the sugar in and blend briefly. Add the dry ingredients and blend on low until somewhat smooth. Add very hot coffee or boiling water and pulse to combine, careful not to let the hot liquid splash back on you.
Pour into cake pans and bake for about 30-35 minutes, or until toothpick inserted into center comes out clean.
Cool cakes in pans on wire racks for 10 minutes. Remove from pans and cool completely before filling and frosting.
FOR THE CARAMEL
In a small saucepan, heat the brown sugar, butter, and golden syrup (or corn syrup) on medium low heat until mixture begins to boil. Stirring constantly, boil the mixture until the sugar has melted completely, about 5 minutes. You shouldn't see anymore sugar crystals present when you lift the spoon up.
Add the sweetened condensed milk and heavy cream and stir to combine. The caramel will bubbly rapidly so be careful. Keep stirring constantly until the caramel begins to boil again. Continue boiling and stirring until the caramel thickens considerably, about 5 more minutes.
Remove from heat and pour without scraping into a heat resistant container, such as a mason jar. Refrigerate, uncovered, and allow to cool completely before using.
FOR THE FROSTING
In a large bowl or bowl of a stand mixer, whisk the powdered sugar and cocoa. Add the softened butter and boiling water and beat until smooth. Add the melted chocolate and blend until smooth.
Refrigerate frosting for 30 minutes and it will firm up enough to spread.
Putting the Cake Together
Place one cake layer on a cake plate or cardboard cake round on a turn table and ladle 1/3 of the caramel on top. Spread evenly to the edges. Add another cake layer and repeat the process. Add the final cake layer and refrigerate the stacked cakes for one hour (or freeze for 30 minutes). You may have leftover caramel, depending on how much you put on each layer. This can be thinned with a little heavy cream and spooned over ice cream.
Remove the cake from the fridge or freezer and spread the fudge frosting all over the top and sides of the cake. Serve cake at room temperature. Cake will keep at room temperature for 3 days. Do not store it in the refrigerator as the caramel will begin to crystallize.