Almost No Bake Four Layer Mud Pie

Oreos with filling (finely crushed (I use my food processor))

unsalted butter, melted

BAKER'S Semi-Sweet Chocolate (roughly chopped)

canned sweetened condensed milk

Vegetable oil

each) pkgs. JELL-O Chocolate Flavor Instant Pudding

cold milk

tub Cool Whip Whipped Topping (thawed, divided)