1In a large bowl, cream together butter, butter flavor shortening, and both sugars, creaming well. Add eggs and vanilla. In a separate medium bowl, blend flour, baking soda, mashed potato flakes, dried cherries, cashews, and white chocolate chips. Gradually add dry mixture to creamed mixture, blending well. Chill dough for at least one hour or overnight. Preheat oven to 350 degrees F. Drop dough by teaspoonsful onto an ungreased non-stick cookie sheet. Bake approx 11 minutes or until slighty underdone and chewy. Tranfer to wire rack to cool.