Whiz the biscuits to a fine crumb in a food processor, then transfer to a plate. Place honey on a separate place. Dip the rim of the 4 glasses in honey, then in the crumbs. Chill to firm up while you make the milkshakes.

Blend leftover crumbs, honey and remaining ingredients, except the cinnamon quills, in a blender until smooth and combined. Pour into the glasses and serve with cinnamon quills.