Step 1

Preheat your oven to 350°F. Grease a standard 9 x 5 inch loaf pan, and set it aside.

Step 2

In a large bowl, place the flour, xanthan gum, salt, baking powder, baking soda and sugar, and whisk to combine well.

Step 3

Create a well in the center of the dry ingredients and add the melted butter, eggs, and vanilla, then the sour cream, and mix until just combined. Add the mashed bananas (200 g) and fold them into the batter, taking care not to further squish them.

Step 4

Scrape the batter into the prepared loaf pan, and smooth the top with a wet spatula. If you're using the optional banana as a topping, place very thinly sliced bananas (cut lengthwise) on top of the smooth batter, sparingly.

Step 5

Place the pan in the center of the preheated oven. Bake until golden brown on top, and a tester inserted in the center comes out with no more than a few moist crumbs attached.

Step 6

Baking time will be about 50 minutes without the additional bananas on top, and about 1 hour with them. If the loaf is browning too fast for the center to bake fully, tent with foil while it finishes baking.

Step 7

Allow the banana bread to cool in the pan for 10 minutes before transferring to a wire rack to cool completely before slicing and serving.