Preheat the oven to 325F and line a cookie sheet with parchment paper or a nonstick pad.
Whisk together the flours, sweetener, salt, and baking soda. Set aside.
In a small bowl, pour the melted coconut oil over the honey and whisk to combine. Add the egg and whisk to combine.
Pour the wet ingredients into the dry ingredients and stir to combine. Allow to sit about 1 minute (this lets the coconut flour absorb moisture).
Scoop 1 Tbsp balls of dough and flatten into a disc. Use your thumb or the back of a cookie scoop to gently press a well into the cookie. Fill with homemade chocolate hazelnut spread. Repeat with remaining dough.
Bake for 9-12 minutes, until edges are slightly golden and the cookies give off the aroma of toasted hazelnuts.