Pre-heat the oven to 180 degrees,
Line a rectangular or square baking tin with baking parchment,
Measure the oats into a mixing bowl,
Melt the butter, sugar and syrup in a pan,
Pour the melted mixture over there oats and stir well,
Add in the mashed bananas and mix well,
Fold in the frozen raspberry pieces but do not over mix or they will break,
Tip the mixture into the lined baking tray and squash down with the back of a spoon,
Bake in the oven for 20 minutes.
Let the flapjacks cool completely before decorating with the icing.