Preheat oven to 350 degrees F (175 degrees C). In a large bowl, mix together the cookie crumbs and melted butter. Press into the bottom of a 9 inch springform pan.
In a heavy saucepan over low heat, melt the caramels with the evaporated milk. Heat and stir frequently until smooth. Pour caramel sauce into crust, and top with pecans.
In a large bowl, combine cream cheese, sugar and vanilla; beat well until smooth. Add eggs one at a time, mixing well after each addition. Melt the chocolate, and blend into cream cheese mixture. Pour chocolate batter over pecans.
Bake in preheated oven for 40 to 50 minutes, or until filling is set. Loosen cake from the edges of pan, but do not remove rim until cooled to prevent the top from cracking. Chill in refrigerator for 4 hours, or overnight.
