Grease 9x13-inch pan lightly. Dump entire can of pineapple and juice in pan and spread evenly on bottom. Dump and distribute coconut evenly over pineapple.
Dump entire box of cake mix evenly over all. Spread evenly with spatula. Cover entire surface with small pieces of butter. DO NOT MIX.
Bake at 350° F for 45 minutes or until the top is lightly browned. Cool and cut into squares.Servings: 20