How to make
Soak the cranberries in alcohol for a few hours or overnight.
Beat the butter along with the sugar and vanilla, until a fluffy cream is obtained. Add the eggs one at a time, while beating the mixture at all times.
Pour the rum to the resulting creamy mixture, which you have strained from the blueberries and grate the lemon peel, but only the yellow part.
Add the flour in portions along with the baking powder and salt, by sifting and stirring with a spatula or wooden spoon, until it is absorbed and there are no lumps. The stirring is done with smooth rotating movements in one direction.
Roll the cranberries in 1 tbsp. of flour and shake off the excess. Do this in a strainer, so that it's easier for you. Add them to the mixture and stir again.
Pour the mixture into a sponge cake tin, which needs to have been greased and sprinkled with flour in advance (capacity 2 liters). Place it in a preheated oven at 360°F (180 degrees).
Bake the butter sponge cake for about 50 minutes or until it is fully baked.
Once you remove it from the oven, leave it for 10 minutes and then remove it from the cake tin and place it on a wire rack to cool completely - about 30 minutes.
Enjoy!
