Beat the pumpkin, sugar, eggs and oil in a large bowl. Combine biscuit mix and cinnamon; gradually add to pumpkin mixture and mix well. Stir in raisins.
Pour into a greased 15-in. x 10-in. x 1-in. baking pan. Bake at 350° for 25-30 minutes or until a toothpick inserted near the center comes out clean. Cool on a wire rack.
Meanwhile, in a large bowl, beat cream cheese and butter until fluffy. Add milk and vanilla. Gradually beat in confectioners' sugar until smooth. Spread over bars. Store in the refrigerator. Yield: about 3 dozen.