Preheat oven to 425°F and place the frozen pie crust on a high quality baking sheet or in a glass baking pan to defrost while you prepare the filling.
1 (9-inch) deep-dish frozen pie crust
In the bowl of a stand mixer fitted with the paddle attachment, beat the eggs and brown sugar together until combined and slightly frothy, about 1 minute.
3 large eggs, 1 cup brown sugar
Add in the corn syrup and vanilla and beat together for about 1 minute.
¾ cup corn syrup, 1 teaspoon pure vanilla extract
In a separate mixing bowl, whisk the melted butter and cocoa powder together until it forms a smooth chocolate sauce.
½ cup salted butter, ¼ cup unsweetened cocoa powder
Add the chocolate and butter mixture into the egg mixture and beat together until combined, about 1 minute.
Fold in the pecans and dark chocolate chips and then pour the filling into the crust. Only fill to just below the top edge of the crust. If you have extra filling, discard it. Don’t overfill.
1 cup pecan halves, ½ cup dark chocolate chips
Use a fork to gently pop any bubbles on the top of the pie and turn over the pecans that come to the top, if you wish.
Bake for 10 minutes at 425°F, then reduce the heat to 350°F and continue baking for 35-50 minutes, or until the top is a medium brown and the pie jiggles only slightly in the middle. If your crust begins to get too brown you can cover it with aluminum foil to keep it from burning.
Allow the pie to cool completely before slicing and serving with whipped topping (optional).
Whipped topping