1. Pour the raisins into a bowl full of warm water and put them apart.
2. Melt the butter with the sugar and add the eggs, one by one.
3. Mash the bananas and blend them with the Grappa, then combine the two mixtures.
4. Mix the flour, the baking powder, the salt, and the drained raisins.
5. Grease a plumcake tin and bake at 356° F for about an hour, or until a toothpick inserted into the bread comes out clean.
6. Prepare the sweet butter mixing all the required ingredients until they are perfectly blended.
7. Serve the Banana Bread with the sweet butter.