Heat oven to 350°F. Lightly grease two cookie sheets. In large bowl, beat butter and sugars with electric mixer until creamy. Add egg and vanilla; beat well. In separate bowl, combine flour and baking soda; mix well. Add to butter mixture; mix well. Stir in oats; mix well. Divide dough into 4 equal portions. Using hands, pat each portion of dough into a large 1/4-inch thick snowman on cookie sheet. Bake 12 to 14 minutes or until edges are light golden brown. Cool 2 minutes on cookie sheets; carefully remove to wire rack. Cool completely. Decorate as desired with frosting and candy. Store tightly covered.