Preheat oven to 400℉.
Combine the sugar and corn syrup in a small saucepan over medium-high heat. Stir to partially dissolve the sugar. Bring to a boil, reduce heat to low. Simmer two minutes, stirring often. Remove from heat and allow to cool.
In a microwave-safe bowl, combine the chocolate and butter. Microwave on high for 1 1/2 minutes in 30-second intervals stirring between each. Remove from the microwave and allow to cool completely.
In a large bowl, beat the eggs until foamy. Combine with the chocolate and corn syrup mixtures. Stir in the vanilla and pecan halves. Pour into the unbaked pie crust.
Bake at 400℉ for 20 minutes. Lower the oven temperature to 350℉ and bake an additional 25 minutes or until the filling has set. Cool completely before cutting.