Prepare the Dates: Place the chopped dates in a bowl and pour the boiling water over them. Let them soak for about 15 minutes until softened.
Preheat the Oven: Preheat your oven to 180°C (160°C fan)/350°F/Gas Mark 4. Grease and line a 20cm (8-inch) round cake tin with baking paper.
Mix the Wet Ingredients: In a large mixing bowl, cream the softened butter and sugar together until light and fluffy. Add the eggs one at a time, beating well after each addition. Stir in the mashed banana and vanilla extract.
Combine Dry Ingredients: Sift the self-raising flour and baking powder into the wet mixture. Fold gently until just combined.
Add the Dates: Stir the soaked dates (along with any remaining water) into the batter. The water helps keep the cake moist, so don’t skip it!
Bake the Cake: Pour the batter into the prepared tin and smooth the top. Bake for 35-40 minutes, or until a skewer inserted into the center comes out clean.
Cool and Serve: Allow the cake to cool in the tin for 10 minutes before transferring it to a wire rack to cool completely. Serve as is or with a dusting of powdered sugar.