Preheat the oven to 325 degrees F. Line a 9x5-inch loaf pan with parchment paper or grease with coconut oil spray.
In a large bowl, beat together the butter and erythritol until fluffy. Whisk in the eggs, stevia and vanilla extract until fully incorporated.
Whisk in the almond flour, coconut flour, baking powder, and salt.
Grate the zucchini (as shown in the video) and wrap the grated zucchini in cheesecloth or several layers of sturdy paper towels. Squeeze over the sink to release as much moisture as possible.
Fold the grated zucchini into the bowl, and mix well. Fold the chocolate chips and walnuts into the batter.
Transfer the batter to the prepared pan. Smooth the top with the back of the spatula and bake for 50-60 minutes, until an inserted toothpick comes out clean.
Cool completely in the pan prior to flipping out and slicing into 12 pieces.
Note: oven temperatures vary highly and the loaf can easily burn so keep an eye on it starting at 40 minutes. If the top and edges brown too much, check it with a toothpick - it is most likely done at that point! If you need to keep it in longer but the edges are starting to burn you can cover just the edges with foil to help prevent further burning.
Video
Notes
Net Carbs: 4g Serving Size: 1 slice Yields: 12 slices