Place your graham cracker crumbs onto a shallow plate. Dip the rim of your serving glass into a shallow bowl of water, then dip it into the crumbs, completely coating the rim. Set aside.
Put all shake ingredients into a blender.
Pour some milk into the blender to help process the mixture, adding more as necessary. The softer your ice cream, the easier it will be to blend quickly.
Pour into prepared glass. Top with whipped cream and a sprinkle of cinnamon or nutmeg.