For crust: Combine graham cracker crumbs and melted butter; press mixture onto bottom and sides of a buttered 10-inch springform pan (2 inches deep). Bake in preheated 350°F oven 10 to 15 minutes. Set aside to cool.
For filling: In heavy saucepan, melted caramels with evaporated milk over low heat, stirring frequently until smooth. (If desired, dip a few pecans into caramel mixture and set aside to use later as a garnish). Pour caramel mixture over cooled crust; top with toasted pecans.
Combine cream cheese and sugar, mixing on medium speed until well blended. Add eggs, one at a time, mixing well after each addition. Add vanilla. Blend in melted chocolate. Pour mixture over pecans and caramel in crust, starting at outer edge.
Bake in a preheated 350°F. oven 1 hour and 20 to 25 minutes, or until edges begin to crack. Remove from oven and let cool at room temperature for 30 to 40 minutes. Cover and refrigerate overnight. Remove sides of pan and loosen cheesecake with spatula.
For chocolate topping: Melt chocolate morsels on medium heat in microwave. Add evaporated milk (or 2 percent milk and butter; see note). Stir until mixture is smooth.
Spread chocolate topping over chilled cheesecake. Garnish with dollops of whipped cream and pecan halves dipped in caramel, if desired.
Note: If you don’t want to open another can for the 3 tablespoons evaporated milk, you can substitute 3 tablespoons 2 percent milk and 2 teaspoons butter.
To toast pecans: Put 1 tablespoon butter or margarine in a 9-inch pie plate. Microwave until melted. Stir in 1 cup pecans, tossing to coat. Microwave on HIGH 2 to 2 1/2 minutes. Let stand 5 minutes.