Step 1

Preheat the oven to 375° and lightly grease a 6" pie plate.

Step 2

In a medium bowl, cream the butter, shortening, brown sugar and granulated sugar together. Beat very well, about 45 seconds. Add the egg yolk and vanilla and beat until combined.

Step 3

In a small bowl, whisk together remaining ingredients (except chocolate chips) and add it in 2 batches to the creamed butter, beating just to combine.

Step 4

Stir in the chocolate chips. Press the dough into the pie plate and press it evenly flat. Bake for 30-33 minutes, until the middle is slightly underdone (it will set up as it cools).