Cut four 14"x12" pieces of waxed paper or plastic wrap; set aside. Cream shortening, sugars, and peanut butter in a large bowl. Beat in vanilla and eggs until light and fluffy. In a large bowl, combine dry ingredients. Gradually stir flour mixture into egg mixture until blended. Divide dough into 4 equal pieces. Shape each piece into an 8 to 10 inch roll. Wrap each roll in 1 piece of waxed paper or plastic wrap. Place wrapped rolls in a freezer container with a tight-fitting lid, or wrap airtight in a piece of foil. Label and date. Store in freezer. Use within 6 months.
To make cookies: Slightly thaw dough. Preheat oven to 350F. Cut dough into slices or chunks. Roll each piece into a ball. Place balls on an ungreased baking sheet about 1 1/2 inches apart. Use fork tines to flatten cookies in a crisscross design. Bake 8 to 10 minutes until lightly browned around edges. Remove cookies from baking sheet and cool on wire racks.