Before starting: Preheat your oven to 350° F. and remove chocolate ice cream and Cool Whip from the freezer so it begins to soften slightly to make spreading easier.
Crunchy Cookie Layer:
Crush Oreos and add to butter. Crush about 10 Oreos, to get about 1 cup of crushed crumbs. In a small bowl, mix with melted butter.
Bake cookie crumbs. Spread buttery Oreo crumbs on a baking sheet that's covered with parchment paper and bake at 350 degrees for 6-7 minutes.
Make Ganache:
Make ganache. In a small, microwavable bowl, add chocolate chips, corn syrup, and vanilla.
Heat heavy cream. Next, warm your heavy cream until just boiling, and then pour over the chocolate chips. Allow it to sit for 2-3 minutes and then whisk until smooth, chocolate ganache forms.
Build Ice Cream Cake:
First layer. In a loaf pan, add parchment paper to completely cover the pan. (You want to do this so when the entire cake is frozen, it's easy to pull up out of the pan, to slice.) Make sure the entire loaf pan is covered with paper before filling. Add 5 ice cream sandwiches on top of parchment paper.
Add chocolate ice cream layer. In a medium-sized mixing bowl, stir chocolate ice cream until it is smooth enough to spread on top of the ice cream sandwiches, and then freeze loaf pan of ice cream for 20 minutes.
Add ganache. Remove theloaf pan from the freezer and pour on cooled ganache on top of the chocolate ice cream, and then freeze for about 10 minutes.
Add crunchies. Sprinkle on the crushed, baked Oreo cookie crumbs on top of the fudgy layer and then freeze for 2 hours.
Add 2nd ice cream sandwich layer. Next, add 5 more ice cream sandwiches on top of the crunchy cookie layer.
Top with Cool Whip. Spread Cool Whip layer on top of the ice cream sandwiches.
Garnish with Oreos. If desired, crush (in to small pieces) about 4-5 Oreo cookies and sprinkle on top of ice cream sandwich cake. Cover with plastic wrap and freeze for 3-4 hours (or overnight to be safe) until cake is fully frozen and thick enough to slice.
Slice and serve. Remove the cake from the loaf pan by grabbing parchment paper and lifting it out. Peel the parchment paper from the sides of the cake and slice.