1) Preheat the oven to 180C/Gas 4. Butter and flour a 23-by-12 1/2cm loaf pan.
2) In a large bowl, beat the 115g of butter and the sugar at a medium speed with an electric mixer until creamy. Add the eggs, vanilla and buttermilk, beating well.
3) In a small bowl, combine the 210g of flour, baking powder and bicarbonate of soda. Slowly add to the wet ingredients.
4) Add the mashed bananas and fold in the sultanas. Pour into the prepared pan and bake for 50-60 minutes.
5) Allow the bread to cool in the pan for 10 minutes. Remove from the pan and leave to cool completely on a wire rack.
1) Cut the banana bread into slices. Spread peanut butter over half of the slices. Top with the remaining slices to make a sandwich.
2) Cut each sandwich into the desired shapes or sizes. Roll the edges in chopped peanuts and serve.