Mix dry ingredients: Whisk the almond flour, protein powder, finely chopped walnuts, coconut flour, and cinnamon together in a medium bowl.
Make dough: Beat the butter and granulated sweetener until creamy. Beat in the egg, maple syrup, and maple extract, then beat in the dry mixture until it comes together as a dough.
Roll dough: Dust parchment or a silicone mat with coconut flour. Pat the dough into a rough circle, lay parchment on top, and roll between the 2 pieces of parchment paper to ¼ inch.
Cut out cookies: Cut your leaves and lift each one with a small offset spatula onto a lined baking sheet. Gather the scraps, re-roll, cut the rest.
Freeze the cut cookies on the pan for 20 minutes. Preheat the oven to 325°F.
Bake 12–14 minutes, until the edges are lightly golden. Cool completely on the pan — they're soft coming out and firm up as they cool.
Make glaze: Combine the brown sugar-free sweetener, butter, and cream in a small saucepan over low heat. Stir constantly until the sweetener dissolves and it looks like caramel, 3–4 minutes. Off the heat, let it cool a minute. Whisk in the maple syrup and maple extract, then the powdered sweetener a little at a time, then the nutmeg. It should be light brown, pourable, and ribbon off the whisk easily. Thin with another teaspoon of cream if needed.
Dip cookies in glaze: Working quickly and carefully, dip one side of each cooled cookie, let the excess drip off, set on a rack, and scatter walnuts on while the icing is wet. Sets in about 45 minutes.