Remove the ice cream from the freezer to soften while you prepare the crust.
Remove and discard the cream filling from the oreos. Pulse the cookies in a food processor until the crumbs are fine and resemble dirt.
Set aside ½ cup of the crumbs. Mix the remaining crumbs with the melted butter until well combined.
Press the crumb mixture evenly into the bottom of a 9x9-inch pan or dish to form the crust.
Spread the softened ice cream over the crust in an even layer.
Sprinkle the reserved cookie crumbs evenly over the top of the ice cream. Clean off the edges of the pan for a tidy finish.
Freeze the tart for at least 2 hours, or until firm.
Before serving, decorate with fresh mint, berries, and gummy critters. Slice and serve.