In large bowl, cream butter and sugar; add pumpkin, eggs and vanilla extract.
Stir in flour, oats, spice, baking powder, baking soda, salt and walnuts.
Spread batter into greased and floured 15 x 10-inch jellyroll pan or 2 (8-inch)
square baking pans.
Bake for 25 to 30 minutes (30 to 35 minutes for 8-inch pans).
Immediately sprinkle butterscotch morsels on brownies; let stand 5 minutes.
To frost, gently spread morsels to cover brownies.
In small saucepan, melt chocolate chips over low heat. Drizzle over frosted brownies
in a spiral design. While still warm, lightly drag the edge of a knife or thin metal
spatula from the center of the spiral to the edge of the pan. Repeat motion at spaced
intervals to make a spider web pattern.