Stir the hazelnut spread with 2 tablespoons of chopped hazelnuts. Scoop 12 rounded teaspoons onto a parchment-lined plate and freeze for 20 minutes.
Heat the oven to 350°F and line a baking sheet with parchment. Whisk the almond flour, cocoa powder, coconut flour, baking soda, and sea salt together.
Beat the softened butter and allulose until creamy. Beat in the egg and vanilla, then stir in the dry ingredients.
Fold the dark chocolate chips and remaining toasted hazelnuts into the dough.
Divide the dough into 12 portions, flatten each one, and place a frozen hazelnut center inside. Seal the dough completely around the filling.
Arrange the cookies on the pan, flatten them slightly, and bake for 10 to 12 minutes until the edges are set.
Cool for 15 minutes before serving so the cookie firms around the soft chocolate hazelnut center and crunchy nut pieces.