Prepare the royal icing. Rinse mixing bowl with lemon juice or white vinegar.
Beat the egg whites and cream of tartar at high speed until they are foamy.
Add the sugar, lemon juice, and green food coloring.
Beat at high speed until thick and fluffy.
Transfer royal icing to a piping bag that has been fitted with a star tip. Set aside.
Fill each ice cream cone with M & m’s.
Pipe around the open edge of the sugar cone, and gently place a cookie (upside-down) over the icing.
Carefully and slowly flip the cone and cookie to create the tree base.
Pipe the “leaves”. Beginning at the base of the tree, add small dollops of the green royal icing over the cone by squeezing the bag, releasing a small amount of icing, then lifting straight up off the dollop. Continue this technique until the entire surface of the cone is covered.
Decorate the tree using star candies for the tops, licorice rope as a garland, and assorted candies or sprinkles as ornaments.
Allow the trees to set and harden at room temperature for an hour.
Notes
Storage:Trees are best stored in an airtight container at room temperature or in the refrigerator for up to 5 days. Chocolate-dipped sugar cones are a great alternative to a plain sugar cone.Tips:
Pour the powdered sugar through a sifter or sieve to remove any clumps. This step isn’t necessary, but it makes a really smooth icing.
Your egg whites must be at room temperature in order for them to whip up properly! Let 'em sit out for an hour or so before you get started.
Add less green food coloring to your white frosting for a light green tree, or add extra drops to make a dark pine color.
Using a star tip or leaf tip on your piping bag will make your Christmas tree cones look more realistic with a leaf-like pattern.
Start icing your sugar cones from the rim of the cone and move upwards in vertical rows all the way up to the top of the cone, repeating this process until you cover the whole thing with green frosting. This technique will keep the tree shape neat and consistent.