Preheat the oven to 350°F (175°C). Lightly grease a 9×5-inch loaf pan and set aside.
In a large bowl, whisk together 2 cups Bob’s Red Mill gluten free flour, 1 teaspoon baking powder, 1 teaspoon baking soda, and 1/4 teaspoon salt. Set the dry mixture aside.
In a separate large bowl, cream 1/2 cup (1 stick) softened butter and 1/2 cup sugar until light and fluffy (about 1–3 minutes by hand or with a mixer).
Beat in the 2 eggs, one at a time, mixing until each is incorporated.
Stir in 2 tablespoons milk and 1/2 teaspoon vanilla.
Mash 4–5 very ripe bananas until smooth and measure about 1 1/2 cups. Stir the mashed bananas into the wet mixture until evenly combined.
Add the dry flour mixture to the wet ingredients and gently stir or fold just until no large streaks of flour remain. Do not overmix.
Fold in 1/2 cup chocolate chips (or 1/2 cup of your favorite mix-in).
Pour the batter into the prepared loaf pan and smooth the top with a spatula.
Bake in the preheated oven for 50–55 minutes, or until a toothpick inserted into the center comes out clean or with a few moist crumbs (not wet batter).
Let the bread cool in the pan for at least 15 minutes, then turn it out onto a wire rack and cool an additional 30 minutes before slicing and serving.