Combine the Oreo crumbs, brown sugar, and melted butter in a small bowl.
When the mixture resembles wet sand, divide it between 12 muffin tins (or 3 mini cake pans), making sure to pack it tightly so the crust doesn’t fall apart. Set the pan in the freezer until ready to use.
For the filling
Add the heavy cream to the bowl of a stand mixer fitted with the whisk attachment. Beat the cream on medium-high speed until it forms stiff peaks.
Switch to the paddle attachment and add the cream cheese, sugar, crème de menthe, and vanilla. Mix on low speed until combined, making sure to scrape down the sides of the bowl a few times.
Divide the mixture between the muffin tins and place in the refrigerator for at least 4 hours. Remove from the fridge and serve chilled. Garnish with Oreo, mint, or whipped cream, if desired.