Preheat oven to 325 degrees F.
Spray or grease a jelly roll pan. To make cleanup easy, line with parchment paper.
Combine cake mix, pecans, shortening, caramel topping (1 cup), and hot water with mixer.
Spread evenly in the greased jelly roll pan.
Bake for 30 to 35 minutes.
Meanwhile, mix powdered sugar, butter, 3 Tablespoons caramel topping and milk in mixer until smooth.
Once cake has cooled, spread caramel frosting evenly.