Combine flour and baking soda and set aside.
In large bowl mix with electric mixer: peanut butter, butter or margarine, sugar and vanilla until creamy. Add egg until light and fluffy. Gradually add flour mixture. Stir in 3/4 cups chocolate chips [and optional nuts].
Press dough into greased pizza pan. Bake at 350 degrees F for 20-25 minutes or until done. Cool completely.
Spread marshmallow fluff on cookie. Melt 1/4 cup chocolate chips. Drizzle in circular pattern on top of marshmallow fluff. Draw a knife through chocolate drizzle to create web effect.
Decorate with Halloween candies or decorations.
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