Preheat oven to 350. In a 9 or 10 inch pie plate place premade pie crust, crimp edges, set aside. In a medium size saucepan combine butter and chocolate over medium heat, stirring until chocolate and butter melt, about 5 minutes. Remove from heat and add the sugar and corn syrup, stir to combine well. Add the beaten eggs, vanilla and salt, stir to mix together into a thick smooth chocolate filling, add pecans stir well and pour into piecrust. Bake 40 minutes.