In a large bowl, beat the heavy cream with a mixer at high speed until soft peaks form. Gradually add the sugar, beating until combined. Reduce the speed to low and add the vanilla.
In a large serving bowl, combine the ice cream and whipped cream. Pour in the coffee and allow the ice cream mixture to soften slightly. Gently stir before serving. Top each serving with 1/2 teaspoon liqueur, if using, and sprinkle with cinnamon.