Preheat oven to 180&grad;C. Line a 24cm spring-form, loose-base baking tin.
Sift flour, baking powder, bicarbonate of soda and cocoa powder into a mixing bowl. Add the orange zest.
Melt the butter slowly and gently in a pan over a low heat, along with Kinnie or your alternative fizzy soft drink.
Meanwhile, beat the eggs and add the orange juice to them.
Pour the melted butter and Kinnie mix into the dry ingredients, give a couple of stirs and add the egg mix as well. Beat all ingredients together well, making sure there are no dry bits left.
Pour the cake mix into the prepared tin and bake for 35-40 minutes until risen. Test with a cocktail stick to ensure centre isn't gooey and uncooked. It will be more moist than a regular sponge though.
Cool for 10 minutes in the tin, then turn out on a wire cooling rack.
Topping: while the cake cools completely, place the ricotta in a bowl, along with 2 tbsps icing sugar and 2 tbsps single cream. Beat with a hand mixer until blended. If too stiff, add more cream; or if too runny, add a bit more icing sugar. It should be viscous but not overly runny otherwise it will drip off the cake.
When the cake is cool, scrape over the topping, evening it out with a knife.
Sprinkle with some orange zest and grated chocolate if you wish.
After serving, keep the cake covered in the fridge as it has a ricotta & cream topping. You can also use soft cream cheese like Philadelphia instead of ricotta.
Enjoy!