Set out your ice cream to soften while you prepare the other ingredients. If at any point, it starts to melt too much, put the ice cream in the refrigerator. Crush 10 ounces of Oreos (two rows of cookies, plus another cookie or two) in a large ziplock bag, or use your food processor to make them into crumbs. Place the crumbs in a medium bowl to use them for the crust. (Save most of the remaining cookies to crush them later for the other parts of the cake.)
Melt four tablespoons of butter in a small pan on the stove or in the microwave using a microwave-safe bowl. Add the melted butter to your Oreo crumbs and stir to combine.
Press the crumbs into the bottom and slightly up the sides of an ungreased 9-or-10-inch springform pan. Freeze the crust while you prepare the rest of the cake. Crush or crumble most of the remaining Oreo cookies and set the crumbs aside.
To make the caramel, add the half stick of butter, sugar, salt and cream to a medium, heavy-bottomed sauce pan (I used my stainless steel pan.) Stir to combine. Over low heat, melt the ingredients while stirring slowly and gently. Don't rush this part.
When the ingredients are melted, increase the heat to medium-low, stirring, and let the mixture come to a low boil. Stop stirring and let the caramel simmer for seven minutes without touching it. Keep an eye on it, and if it smells like the mixture is burning, lower the heat a bit.
Off the heat, stand back and carefully and gently stir in the vanilla (it will splash) without scraping the sides (to avoid grainy caramel). Set the caramel aside to cool. It should look like thick liquid, rather than soft ball-stage caramel.
To make your whipped cream, beat the whipping cream and confectioners sugar in a clean, medium stainless steel bowl with a mixer until the cream is about half way to being stiff. Add in the vanilla extract and continue beating until stiff peaks form.
In a large bowl, stir your ice cream with a wooden spoon until it has a smooth, soft, consistency. Fold in your whipped cream and gently combine it with the ice cream. If the caramel is cooled off enough to not melt the ice cream, proceed to assemble the cake. Otherwise, chill your ice cream mixture until the caramel is ready.
When the caramel is cool enough, assemble your cake. Using a spatula, place half of your ice cream mixture on top of your crust in the springform pan. Drizzle or spoon the caramel sauce all over the ice cream layer, making sure it's evenly dispersed. Try not to have clumps of caramel, or they'll freeze into solid chunks. (Spread the caramel with a knife if needed.)
Sprinkle on enough Oreo crumbs to cover the caramel. Gently add the remaining ice cream mixture over the crumbs, being careful not to disturb the layer underneath. Gently spread the ice cream evenly.
Freeze the pan, uncovered, for 15 minutes, to allow the ice cream to set a bit. Sprinkle on additional Oreo crumbs for garnish. Then cover the pan with plastic wrap, plus a layer of foil. If you have a leaky springform, you might want to wrap the bottom of the pan with foil as well.
The cake will need at least 8 hours to set in the freezer, but it's even better the next day or two, when the crust is softer, and the flavors have melded. Thirty minutes before serving, let the ice cream cake thaw on the counter at room temperature so that you can slice it.
Freeze any leftover cake in the springform, covered with plastic and foil, for up to seven days.
The ice cream cake will have the best taste and texture 1-2 days after you make it, because the crust softens, and the flavors meld.
If buying ice cream in 1.5-quart containers, you will need one full one plus ⅓ of another.
If you are buying caramel sundae sauce, you will need about 9 ounces.
To substitute frozen whipped topping for the homemade whipped cream, use 2 cups of whipped topping.
To make this in a 9x13 pan, use 1.5 times the ingredients.
Try variations such as coffee ice cream with chocolate sauce, chocolate ice cream with strawberry sauce, or vanilla ice cream with hot fudge and chopped Reese's cups.