Preheat oven to 350 degrees F/ 180 degrees C. Grease a 10 inch/ 25 cm loaf pan and line it with a sheet of parchment paper so that it hangs on the long sides.
In a food processor combine almonds, walnuts and xylitol. Pulse for few minutes, until the nuts age finely ground. Combine the mixture with the coconut flour and baking powder and mix very well. Set aside.
In a large bowl beat the eggs with an electric mixer until foamy. Add the oil and the sour cream and beat shortly to combine. Add the grated zucchini (if they are too wet, squeeze some of the water out). Mix with a rubber spatula until incorporated.
Gradually add the dry mixture and fold it gently with the rubber spatula until incorporated.
Transfer the batter into the prepared pan. Bake for 30-40 minutes or until a toothpick inserted in the centre comes our clean or only with few crumbs.
Let the cake cool and then cover it with chocolate glaze, if you want.
Melt the chocolate on a double boiler together with the cream. Pour it on top of the cooled zucchini bread.
You can use other keto sweeteners by choice instead of xylitol, if you prefer.