Modified from website
3-4 medium overripe bananas, mashed (1 1/2 cups)
1/3 cup butter, melted
3/4 cup sugar
1 large egg, beaten
1 teaspoon vanilla extract
1 1/2 cups gluten-free all purpose flour
3/4 teaspoon baking soda
3/4 teaspoon baking powder
1/2 teaspoon salt
Preheat oven to 350°F. Grease an 8x4-inch loaf pan generously with cooking spray. In a large mixing bowl, add mashed bananas and stir in melted butter, sugar, egg, and vanilla. Mix the dry ingredients and combine: In a smaller bowl, add flour, baking soda, baking powder, and salt and combine. Add the flour mixture to the larger bowl with the wet ingredients and stir until fully combined.
Pour batter into the prepared loaf pan, scraping the bowl to assist. Bake for 50 minutes to 1 hour, or until a tester comes out clean.