Place butter in a small bowl and cover with a napkin to avoid splatter. Microwave for 30 to 45 seconds.
Crack eggs into a medium-sized bowl. Whisk vanilla into eggs until fluffy. Add melted butter, and whisk to combine.
In another larger bowl, whisk flour, sugar, baking soda, baking powder, salt, and cinnamon.
Stir the wet ingredients into the dry ingredients until combined.
Fold the mashed banana and huckleberries into the batter.
Grease and flour a loaf pan and pour the batter into it.
Bake loaf for 1 hour. Loosely cover with foil during the last 30 minutes of baking to avoid over-browning.
After an hour, test to make sure that the loaf is cooked all the way through. Do this by inserting a toothpick into the center of the loaf. The toothpick should come out clean.
If it needs to continue to cook, turn the temperature down to 300-degrees F. and cover loosely with the foil as it continues to cook. Check every 5 minutes until a toothpick comes out clean.
Cool for approximately 15 minutes then carefully invert the loaf onto a wire rack. Cool completely before slicing.