In a bowl, stir the peanuts into the ice cream. Working quickly, place 1 tbsp. ice cream onto half of the crackers (refreeze the ice cream if needed). Press the remaining crackers on top.
Freeze the sandwiches until set, about 30 minutes. Roll the edges of each ice cream sandwich in the nonpareils to coat. Serve immediately, or wrap individually in plastic wrap and freeze for up to 1 week.