Preheat oven to 350. Lightly grease 13 x 9 x 2" baking pan; set aside. In large bowl combine 3/4 c sugar, 1/2 c flour and 1/2 c nuts; add 1/4 c melted butter and mix well. Press onto bottom of prepared pan. Bake 10 minutes or until set; cool slightly.
In large bowl ceam remaining 1/2 c butter and 1/2 c sugar; beat in eggs and vanilla. combine 1 c M&M's and remaining 3 T flour; stir into creamed mixture. Spread over cooled crust.
Combine coconut and remaining 1 c nuts; sprinkle over batter.
Sprinkle remaining 3/4 c M&M's over coconut and nuts; pat down lightly. Bake 25-30 minutes or until set. Cool completely. Cut into bars. Store in tightly covered container.