First, bake the box lemon bars according to the directions on the box in a 9 x 13 inch casserole dish. Once baked allow to cool fully.
Top the baked lemon bar with a layer of lemon pudding.
After the lemon pudding add the whipped topping then smooth it into one even layer using an offset spatula.
Next, Sprinkle over the crushed wafer cookies.
Allow the lasagna to set in the fridge for a minimum of 12 hours, preferably overnight.
When ready to serve, top the lasagna with mini marshmallows or marshmallow fluff. Torch the marshmallow to toast them if desired then slice into squares and enjoy!