Place oil and popcorn kernels in the bottom of a heavy bottomed pan and turn the heat to medium-high. Cover with a lid, but leave it open slightly to allow steam to escape. Once the popping of the kernels has stopped remove pan from heat and pour popcorn into a large bowl.
In a separate bowl combine the chocolate chips and peanut butter. Microwave for 1 minute, remove from microwave and stir. Microwave an additional 20 seconds and stir again. Keep doing this until the chocolate and peanut butter are smooth and creamy. Stir in the vanilla.
Pour the chocolate mixture over the popcorn and stir gently to coat.
Pour 1/3 of the popcorn into a gallon sized zipclose bag and pour in 1 cup of the powdered sugar. Shake gently to coat all the popcorn. Pour onto a sheet of wax paper to cool. Repeat with the remaining popcorn and powdered sugar.