Heat the oven to 200C/fan 180C/gas 6. Line a 12 hole muffin tin with muffin cases. Tip the flour, baking powder, almonds and sugar into a large bowl. Mix the banana with the almond butter, eggs, buttermilk and vanilla until the mixture is smooth, use a hand blender if you have one. Fold the wet mix and dry mix together, don’t worry if it looks a bit lumpy. Divide the mixture between the cases and sprinkle a few almonds onto each. Bake for 15-20 minutes, or until the muffins have risen and are golden and cracked on top. Cool.