Preheat oven to 375°F (190°C) and prepare a 9-inch (23 cm) cake pan with butter and flour.
In a medium bowl, sift together the all-purpose flour, granulated sugar, baking soda, salt and cocoa powder.
In a larger bowl, blend the softened butter and buttermilk until light and fluffy. Add the eggs in one by one, then stir in the vanilla extract.
Slowly fold the flour mixture into the butter mixture, stirring just until incorporated. Pour in the hot water and mix again until combined.
Pour batter into cake pan and bake for 25-30 minutes or until a toothpick comes out clean when inserted into the center of the cake. Cool for 10 minutes in the pan before turning out onto a wire cooling rack.
Serve with ice cream, caramel sauce, and chocolate shavings for an extra indulgent treat! Enjoy your very own homemade Chocolate Cake!