Spray the bottom of a 9x13 pan with vegetable oil.
Begin laying graham crackers in the bottom (whole) until you coat the bottom. You will have to break up some larger pieces for the edge of the pan.
Mix the pudding with milk and extract. NOTE use only 2.5 cups of milk rather than what the pudding box instructs. Stir.
In about 2 minutes the pudding thickens.
Zest 1 Tbs. of the whole lemon and add it to the pudding mix.
Put ½ of the pudding mix on top of the first layer of graham crackers.
Follow with another layer of graham crackers.
Finish with the remaining pudding.
Thin slice some lemon pieces for garnish on top. *
Cover with plastic wrap for 4 hours in the refrigerator
Slice and serve
Other topper ideas include coconut, fruit or sprinkles!