Line a 9 × 13 inch pan with parchment paper, leaving wings on the side, and set aside.
In a saucepan over medium-low heat, combine butter, brown sugar, powdered sugar, peanut butter, vanilla and salt. Stir frequently until butter is melted and all ingredients are combined.
Remove from heat and stir in graham cracker crumbs. Spread into prepared pan, tapping down on counter to level it out. Place in fridge for at least 30 minutes.
Gently melt chocolate chips and oil in microwave in 30 second intervals, stirring well in between each interval until smooth. Don't overheat the chocolate. Spread the chocolate over the peanut butter mixture, tapping down on the counter again to smooth out and get rid of any air bubbles.
Chill for at least one hour. Cut bars into squares after they have chilled. Lift bars out of pan using parchment paper wings.
Video
Notes
You'll need approximately 14 whole graham crackers (rectangles) to make 2 cups of crumbs.
These are pretty generously sized squares. If desired, cut into 32 squares.
Bars can be frozen up to three months in airtight container.
If desired, substitute sunflower butter or crunchy peanut butter for the creamy peanut butter. Milk chocolate chips can be substituted for the semi-sweet chips.
Store leftover bars in the refrigerator or freezer in an airtight container with parchment or waxed paper between layers.