Preheat oven to 350 degree F. Grease a 10-inch springform pan; set aside. For crust, in a medium bowl stir together brownie mix, the 1 egg, and the water. Spread into the bottom of prepared springform pan. Bake in preheated oven for 15 minutes.
Meanwhile, in a medium saucepan combine caramels and evaporated milk; cook and stir over medium-low heat until caramels are melted and smooth;. Remove from heat. Remove 1/2 cup of the melted caramel mixture; cover and refrigerate until serving time.
For filling, in a large mixing bowl beat cream cheese and sweetened condensed milk with an electric mixer on medium speed until combined. Add the 3 eggs, all at once, beating on low speed just until combined.
Pour filling over brownie layer. Drizzle remaining melted caramel mixture over filling. Swirl gently with a knife. Bake in preheated oven about 45 minutes or until center appears nearly set when gently shaken.
Cool in pan on a wire rack for 15 minutes. Loosen edge from side of pan; cool for 30 minutes more. Remove side of the pan; cool cheesecake completely. Cover; chill for at least 4 hours or up to 24 hours before serving. (Cake may crack where caramel mixture is swirled in.)
Before serving, heat reserved caramel mixture; drizzle over cheesecake. Sprinkle with chopped toffee bar. Makes 16 servings.