Heat the oven to 180ºC. Grease a 12 cup muffin tin.
Sift the flour and cinnamon into a mixing bowl and stir in the sugar.
Stir in the egg, oil, pecans, banana and pineapple and stir until the mixture is well combined, but still slightly lumpy.
Spoon the mixture into the tins, filling them by two-thirds.
Bake for 30-35 minutes, until risen and golden.
Leave in the tins to cool for 5 minutes, then place on a wire rack to cool.
For the lemon cream
Beat the butter with an electric whisk until creamy.
Gradually beat in the confectioners’ (icing) sugar, followed by the cream, lemon juice and vanilla.
Beat well until light and fluffy.
Invert the muffins and spread with the lemon cream.
Sprinkle a few chopped nuts over the top of the muffins.