Salted caramel and chocolate cake

Name: Salted caramel and chocolate cake
Prep time: 40 min
Cook time: 1 h 45 min
Total time: 1 h 45 min
Yield: 12 slices
Ingredients: 140 g butter; 200 g plain flour; 280 g brown sugar; 70 g Dutch cocoa powder; 1 tsp bicarbonate of soda; 200 g brewed coffee; 70 g canola oil; 2 eggs; 150 g buttermilk; 1 tsp natural vanilla extract; 80 g unsalted butter; 120 g double cream; 50 g dark brown sugar; 50 g caster sugar; 50 g pure maple syrup; 1 tsp vanilla bean; 1 tsp sea salt; 600 g whipped cream