In a small bowl, mash bananas and dark brown sugar together using a fork. Let it sit for 10 minutes.

In a medium bowl, whisk together brown rice flour, sweet rice flour, baking powder, salt, and xanthan gum.

Add milk, eggs, vegetable oil, vanilla extract, and the banana mixture to the dry ingredients.

Stir until a batter forms. If the batter is too thick, add an additional tablespoon of milk.

Lightly oil a flat griddle pan and heat it over medium-high heat until hot but not smoking.

Pour the batter onto the griddle into rounds, approximately 1/4 cup each.

Cook until bubbles appear all over the surface of the pancake and begin to pop, approximately 3 minutes.

If desired, add a sprinkle of chocolate chips or blueberries to the cooking pancakes.

Flip the pancakes and cook for another 1 to 1 1/2 minutes.

Serve the pancakes with butter, maple syrup, sliced bananas, blueberries, or chopped nuts, if desired.