Preheat oven to 350°F. If using a homemade pie crust, line pie pan with pie dough and press into bottom of pan and up the sides. Trim overhang to ½ inch and tuck overhang under itself. Crimp down evenly around the dish using your fingers. Chill for 15 minutes wrapped in plastic wrap.
Prick bottom of crust and bake for 18 minutes or until lightly golden around the edges. Remove from oven to cool and set aside.Reduce oven to 325°F.
Combine 2/3 cup chocolate chips and butter in a bowl and melt in microwave. Stir in canola oil and cocoa until smooth and set aside.
In a separate bowl, mix together brown sugar, eggs, vanilla extract and salt until smooth. Whisk chocolate mixture into sugar mixture. Stir in flour and remaining chocolate chips until combined.
Spread walnuts in bottom of pie crust. Pour batter over the top and smooth to level.
Bake until a toothpick comes out with just a thin coating of batter on it, about 20-25 minutes. Slice and serve warm. Can be rewarmed in the oven at 300°F for about 10-15 minutes.
Recipe courtesy and reprinted with permission of California Walnuts Board