Line a 9x13 inch dish or pan with 2 layers of plastic wrap, letting it hang over the edges. This is important and helps you remove the ice cream cake to slice!
Set the ice cream out - you want it to soften enough to be “spreadable.” It should not be liquid, but should be thick and starting to melt like frosting.
Coarsely crush the oreos. You can do this in a resealable bag and crush with your hands or a rolling pin. You can also toss them in your food processor and pulse a few times. You don’t want small crumbs, but larger chunks.
Place the crushed cookies all over the bottom of the pan in the plastic wrap. Spread them evenly to create a crust. Take one of the ½ gallons of ice cream and spoon it on top of the cookies. I spoon it all over, then use a large spoon to spread it around. You don’t want to spread it too much and lift all the cookies - but don’t worry, a few cookies will lift! It’s no big deal, the cake will still turn out.
Stick the cake in the freezer for a minute while you unwrap the ice cream sandwiches. Remove the cake and then stick the sandwiches on top in a single layer. The last two sandwiches will fit if they are cut in half. They should cover the cake completely.
Spread the other ½ gallon of ice cream over the sandwiches. You may not use all of the ice cream - use as much as you can or you wish. Cover the dish in plastic wrap tightly. Place in the freezer and freeze for at least 2 hours or even overnight. You can make this a few days ahead of time too!
Remove the cake 20 minutes or so before serving. Melt together the 6 ounces of chocolate and the coconut oil. I do this in a bowl in the microwave in 30 second increments, stirring after each, until melted.
Remove the cake from the pan by the plastic wrap overhand. Drizzle the melted chocolate over top. Sprinkle with crushed candy cakes. Slice and serve!