If desired, for a cookie-crumb rim, moisten the rims of 2 chilled cocktail glasses with water. Place cookie crumbs on a plate; dip rims in crumbs. Set aside.
Fill a mixing glass three-fourths full with ice. Add the remaining ingredients; stir until condensation forms on outside of mixing glass. Strain mixture into 2 chilled cocktail glasses.
Test Kitchen tip: You may substitute 1 ounce pumpkin flavoring syrup for the simple syrup and pumpkin pie spice. Look for flavoring syrup in the coffee section. To make ahead: Prepare a martini mix of vodka, milk, cream, syrup and liqueur. Shake mix before using; pour 1 cup into the mixing glass for each batch of drinks. Add spices and proceed as directed.