Pre-heat the oven to 355 ºF (180 ºC) and line a loaf baking tin with greaseproof/baking paper. (Dimensions of the loaf tin: 8 inch/21cm long, 4inch/11cm wide and 3inch/7cm high.)
Mix the mashed bananas with the lemon juice and set aside.
In a bowl, whisk together the melted butter, caster (superfine) sugar and light brown sugar until pale and fluffy.
Add the mashed bananas, sour cream (or yogurt), eggs and vanilla paste, and whisk until well combined.
Sift together the plain gluten free flour blend, cocoa powder, almond flour, xanthan gum, baking powder, baking soda and salt, and add them to the wet ingredients. Whisk or stir well until you get a smooth batter with no flour clumps.
Add most of the chocolate chips into the banana bread batter, and mix until they’re evenly distributed.
Transfer the batter into the lined loaf tin, smooth out the top, and sprinkle with the leftover chocolate chips.
Bake in the pre-heated oven at 355 ºF (180 ºC) for about 1 hour to 1 hour 10 minutes, or until well risen and an inserted toothpick/skewer comes out clean.
If the banana bread starts browning too quickly or too much, cover it with aluminium foil (shiny side up) about 30 minutes into baking, and continue baking until done.
Once baked, allow it to cool in the tin for 5 – 10 minutes, then remove out of the tin and allow to cool completely on a wire cooling rack. (Although it’s rather wonderful still slightly warm.)
Storage: The gluten free double chocolate banana bread keeps well in a closed container in a cool dry place for 3 – 4 days.
