If you prefer to use graham crackers or other packaged cookies but still want gingerbread flavor, just add 1 teaspoon cinnamon, 1 teaspoon ginger, and 1/2 teaspoon cloves to the batter. Also, obviously make sure that the cookies are vegan if needed.
If you don't have a large muffin tin this recipe can be baked in just about anything that's oven safe. You can use a loaf pan, a 13x9 pan, or even do micro puddings in regular cupcake pans (I've done that last one for a bigger group and they're sooooo cute!).