PREHEAT oven to 375° F. Grease 13 x 9-inch baking pan for Pan Cookies or 8 x 8-inch baking pan for Bars.
BEAT butter in large mixer bowl on MEDIUM-HIGH speed for 2 minutes until creamy.
Add Cookie Mix slowly; mix well on LOW speed for about 15 to 30 seconds. Add egg and cold water; beat on LOW speed for about 15 seconds until dough forms. Do not overmix. Spread dough into pan.
BAKE Pan Cookie for 15 to 20 minutes; Bars for 30 to 35 minutes or until top is golden brown and wooden pick inserted in center comes out clean. Remove to wire rack to cool completely. Store in tightly sealed container or resealable plastic bag.
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