Whisk together flour, baking powder, baking soda and salt. Set aside. Combine butter, brown sugar, egg, vanilla and sour cream. Mix together with mixer. Add dry mixture to wet ingredients and continue mixing. Fold in chopped cashews with spoon.
Pull off and roll pieces of the cookie dough into balls about the size of a walnut with floured hands. Place on ungreased cookie sheet and flatten with a fork or your hands. Bake in preheated 400 degree oven 8 to 10 minutes. Remove, let cool and add icing below. Makes 2 1/2 to 3 dozen cookies.
Coffee Icing Instructions:
Heat butter and coffee on stove or in microwave. Add vanilla and powdered sugar. Mix with spoon or mixer. Spread on cooled cookies.