Add 6 tablespoons butter to a small saucepan set over medium heat, cooking until the butter begins to brown, about 3-4 minutes. Remove from the heat and transfer to a heatproof bowl. Stick in the freezer to chill, 10 minutes, but no longer.Preheat the oven to 350° F. Line a baking sheet with parchment paper.In a mixing bowl, beat together the remaining 6 tablespoons butter, the cooled browned butter, sugar, and vanilla bean powder until combined. Add the egg and mix until combined. Add the flour, baking soda, and salt, beat until combined and the dough forms a ball. If the dough feels too wet to roll out, add 2-4 tablespoons additional flour.Divide the dough in half. Roll out the dough on a floured piece of parchment paper to 1/4 inch thickness. Make sure you're using enough flour or your dough will stick. Cut out the cookies using circle and Christmas tree cutters. Transfer the cookies to a parchment-lined baking sheet. I recommend using a floured spatula to lift the cookies. Cover the baking sheet and place in the freezer until firm, 15 minutes. Roll out the leftover scraps, and repeat with the remaining dough.Bake the cookies on the middle rack of the oven for 8-10 minutes or until just lightly golden. Let cool. Meanwhile, make the icing. In a medium bowl, whisk together the powdered sugar, maple syrup, vanilla, and 1 tablespoon water until smooth and drizzly. If needed, thin the glaze by adding water - 1 tablespoon at a time, until drizzly. Spoon the icing onto each cookie, spreading it to the edges. Let sit to dry. Add the melted chocolate to a sandwich bag and cut a small portion of the corner off. Draw 2 lines onto each round cookie and then a squiggly line up the trees. Press mini M&Ms into the chocolate as "lights" (look through the photos for examples).