Prepare the dough. Melt the butter in any convenient way - in the microwave, in a water bath, in a bowl on the stove. Let the butter cool. Mash the banana in a separate container. Beat the eggs until fluffy, pour in the melted butter, add the bananas. Pour in the flour, baking powder, ground cinnamon and salt, mix thoroughly.
Bake the waffles. Heat up the electric waffle iron. Brush the surface of the waffle iron with vegetable oil. Pour in 1 tbsp of dough and close the lid. Bake until golden for 2-3 minutes.