In a large mixing bowl, beat the pumpkin, sugar, oil, eggs and vanilla. Combine the flour, baking powder, baking soda, and salt; gradually add to pumpkin mixture and mix well. Stir in pecans.
Pour into a greased 15-by-10-by-1-inch baking pan. Bake at 350 degrees for 20–25 minutes or until a toothpick inserted near the center comes out clean. Cool on a wire rack.
Tint frosting orange with yellow and red food coloring. Frost bars; cut into 35 squares. For eyes, place two pieces candy corn on each bar.
In a small microwave-safe bowl, melt chocolate chips; stir until smooth. Transfer to a heavy-duty resealable plastic bag; cut a small hole in a corner of the bag. Pipe dots on candy corn for pupils; decorate faces as desired.