Step 2
Line 13x9-inch pan with foil, with ends of foil extending over sides. Microwave butter in large microwaveable bowl on HIGH 1 to 1-1/2 min. or until melted. Add dry cake mix, 1 egg and 1 Tbsp. lemon juice; beat with mixer until blended. Press 2/3 of the dough onto bottom of prepared pan.