Preheat oven to 350° F.

Lightly grease a 9 x 9 x 2-inch baking pan; set aside.

In large mixing bowl cream butter and sugar. Add egg until well blended; stir in vanilla. Combine flour and baking soda; stir into creamed mixture. Stir in 2/3 cup "M&M's"(r) Chocolate Mini Baking Bits; set aside. Dough will be stiff.

In separate bowl beat together cream cheese, granulated sugar and egg yolk until smooth; stir in cocoa powder until well blended. Place chocolate-cheese mixture in six equal portions evenly in bottom of prepared baking pan.

Place reserved batter around cheese mixture and swirl slightly with tines
of fork. Pat down evenly on top. Sprinkle with remaining 1/3 "M&M's"(r) Chocolate Mini Baking Bits. Bake 25 to 30 minutes until toothpick inserted
in center comes out with moist crumbs. Cool completely before cutting into bars. Store in refrigerator in tightly covered container.