Sift the flour, cinnamon powder, baking powder, and salt twice to ensure even mixing.

Prepare the bananas by mashing one and slicing the other.

Whisk the eggs, then add grape seed oil and sugar. Mix well using a whisk.

Add the mashed banana to the mixture and stir until combined.

Gradually add the sifted dry ingredients while mixing, then pour in the milk and mix until the batter is smooth.

Pour the batter into muffin tins, place a slice of banana on top of each, and bake in a preheated oven at 180°C for 25 minutes.