Preheat the oven to 375°F. In a food processor, place the walnuts, maple sugar, sea salt, cinnamon, and vanilla powder. Blend until it is the texture of sand.
Pour the mixture into a large bowl and make a well in the middle. Crack an egg into the well. Whisk the egg until everything is just combined and sticky.
Line a baking sheet with a Silpat or parchment paper sprayed with a neutral oil. Using an ice cream scoop or your hands, make little cookie balls. Fill a small bowl with water. Dip the fork into the bowl and press the cookies down with a fork. The water will prevent the fork from sticking to the dough. You can press twice to achieve the criss-cross design. Bake the cookies for 13-15 minutes until firm and golden.