Preheat the oven to 200 degrees C. Grease a muffin tin with non-stick spray or line with patty pans.
Sift together the flour, baking powder, cinnamon and salt; set aside. In a medium bowl, cream together the sugar, margarine and egg with an electric mixer until light and fluffy.
Mix in bananas, vanilla, cereal and dates. Blend in dry ingredients until just incorporated. Spoon into prepared muffin cups to about 2/3 full.
Bake for 20 to 25 minutes in the preheated oven, until a toothpick inserted into the centre comes out clean. Cool in the tin over a wire rack for at least 10 minutes before removing muffins from the pan.