Preheat oven to 450º F. Line a large baking sheet, with sides, with non-stick foil.

Cream butter with an electric mixer; add sugars and beat until fluffy. Add dark Karo syrup, light Karo syrup, eggs, and vanilla; beat well. Add cocoa powder and beat well. Place frozen pie shells on prepared baking sheet. Sprinkle 1½ cups pecan pieces in each unbaked pie shell. Pour filling over the nuts; give each pie a couple of taps to release air bubbles.

Bake for 10 minutes in 450° F oven. Reduce temperature to 350° F and bake an additional 40 minutes. Remove from oven and cool to room temperature. Store pies in a Ziploc bag. Can be left at room temperature or refrigerated. Once cut, store pie in refrigerator. These pies freeze beautifully. Yield: Two nine-inch pies.