Gingerbread Sandwich Trees

Directions

1. Cream butter and brown sugar until light and fluffy. Beat in egg and molasses. In another bowl, whisk flour, pie spice, baking soda, ginger and salt; gradually beat into creamed mixture. Refrigerate, covered, until easy to handle, about 2 hours.
2. Preheat oven to 325°. On a lightly floured surface, roll dough to 1/8-in. thickness. Cut with a floured 3-in. tree-shaped cookie cutter. Place 2 in. apart on ungreased baking sheets. Gently press M&M's into half of the cookies. Bake until edges are firm, 8-10 minutes. Remove to wire racks to cool completely.
3. If using vanilla frosting, tint with green food coloring if desired. Spread frosting over bottoms of plain cookies; covered with decorated cookies. Store in an airtight container.