Prepare brownies with water, oil and eggs according to package directions and allow to cool.
While brownies are baking, mix pudding mix with skim milk until smooth. Cover and refrigerate until ready to use.
Cut brownies into small 1"x1" squares. Layer half of the brownies into the bottom of a large trifle dish or clear glass bowl. Top with half of the prepared pudding, half of the cherry pie filling and one tub of the whipped topping.
Repeat layering with the remaining ingredients. Sprinkle the top of the trifle with mini chocolate chips. Refrigerate the trifle until ready to serve.
