Preheat your oven to 350°F / 175°C.
Line a 9x5 inch (22. 5x12. 5 cm) loaf pan with parchment paper, leaving an overhang on the sides to act as handles.
In a large bowl, whisk together the almond flour, coconut flour, baking powder, xanthan gum, and cinnamon until well combined.
In a separate bowl, use an electric mixer to beat the softened butter and erythritol sweetener until light and fluffy.
Beat in the eggs one at a time, followed by the banana extract and almond milk.
Mix until the wet are smooth.
Gradually add the dry flour mixture to the wet mixture, beating on low speed until just incorporated. Be careful not to overmix.
Gently fold in the ¼ cup of chopped walnuts.
Pour the batter into your prepared loaf pan and smooth the top with a spatula.
Sprinkle with additional chopped walnuts if desired.
Bake for 30 to 40 minutes, or until the top is golden brown and a toothpick inserted into the center comes out clean.
Let the bread cool in the pan for 10 minutes before using the parchment paper handles to lift it out.
Transfer the loaf to a wire rack to cool completely before slicing. This step is crucial to prevent it from crumbling.
Don't Overmix: Once you combine the wet and dry , mix only until they are just incorporated. Overmixing can develop the gluten-like properties of the flours and lead to a dense, tough bread.
