Prepare cake batter as directed on package, reducing water to 3 Tbsp. Add dry pudding mix, 1 Tbsp. lime zest and 3 Tbsp. lime juice. (Batter will be very thick.) Drop batter, 2 inches apart, into 64 mounds on parchment-covered baking sheets, using about 1 Tbsp. batter for each. Sprinkle remaining lime zest evenly over half the mounds.