Place 1/2 cup marshmallows in food processor and pulse to small chunks (not a super fine crumb).
1 cup Lucky Charms marshmallows
Combine ice cream and processed marshmallows in a blender and blend until combined. Add 1/4 cup whole marshmallows and combine briefly on lowest speed.
1 cup vanilla ice cream, 1 cup Lucky Charms marshmallows
Pour into glass, top with remaining marshmallows and sprinkles. Serve immediately and enjoy!