Adjust the oven rack to the middle position, pre-heat the oven to 375ºF (190ºC) and line a 2lb/900g (9x5-inch/23x13cm) loaf baking tin with parchment/baking paper.
In a large bowl, combine the mashed bananas with lemon juice, and then add the melted vegan butter, light brown sugar, vegan yoghurt and vanilla. Whisk everything together until well combined.
In a separate bowl, whisk together the plain gluten free flour blend, baking powder, baking soda, xanthan gum, salt, cinnamon and nutmeg.
Add the dry ingredients to the wet, and whisk well until you get a smooth batter with no flour clumps.
Fold in the chopped toasted pecans until they're evenly distributed in the batter.
Transfer the batter into the prepared loaf tin and smooth out the top. If you've set aside any chopped pecans, scatter them over the top.
Bake in the pre-heated oven at 375ºF (190ºC) for about 1 hour - 1 hour 10 minutes, or until well risen, golden brown on top and an inserted toothpick/skewer comes out clean.
Once baked, allow it to cool in the loaf tin for about 10 minutes, then transfer it out of the tin and onto a wire rack to cool.
The banana bread is best served warm or cooled completely to room temperature.
The gluten free vegan banana bread keeps well in a closed container in a cool dry place for 3-4 days.