How to Make It
From 1/2 cup toasted white or black sesame seeds, set aside 2 tsp. Grind remaining seeds in a food processor, scraping bowl occasionally, until they look like damp sand. Blend in 3 tbsp. honey.
Transfer sesame paste to a blender. Add milk and purée, scraping container as needed. Add ice cream and whirl until smooth. For thick shakes, pour mixture into a bowl, cover, and freeze until thick, about 2 hours; blend again.
Pour shake into glasses and sprinkle with reserved sesame seeds.
Make ahead: The sesame paste, up to 2 days, at room temperature.
*Find black sesame seeds at well-stocked grocery stores with spices and Asian and bulk foods, or online. If untoasted, cook seeds in a hot pan over medium heat, stirring, until a light haze forms over pan and seeds crackle (white seeds will also turn golden), 1 to 2 minutes. Let cool.