There are some golden rules to make this gooey wonder at home.
Make the cookie
First things first, you're going to bake the cookie by yourself. You could make do with store-bought ice cream of your favourite flavour, but the cookie needs to bake just the right way for this.
And that's how the cookie crumbles!
No, your cookie won't crumble. An ice cream sandwich needs a soft and gooey cookie and firm and chilled ice cream. If the cookie is hard and the ice cream too soft, their union would be a disappointing mush of melting desire.
The way we see it, there is warm, gooey cookie and hard, chilled-to-the-bone ice cream that's holding off dissolving by a few seconds; when they come together, for a swift second, you almost feel as though they are the same consistency, until the ice cream blends just great with the cookie, melts oh-so gorgeously and tumble into your mouth announcing pure ecstasy.
Layer the ice cream
Shave layers of ice cream off the bowl, do not make balls. Now, construct layers of ice cream on one cookie, close with the other, throw a handful of sprinkles or chocolate chips and bite into it. That's as close to magic as it can get!