How to Make It
In a small saucepan over medium heat, stir together butter, sugar, and corn syrup until sugar is dissolved, 2 to 3 minutes.
Remove from heat and stir in 3/4 cup of milk; transfer to a large bowl.
Add the rest of the milk and whisk in the yogurt. Cover and refrigerate until cold, about 2 hours.
Fill 4 short glasses with the shake and top each with a peaked dollop of whipped topping. Gently place 2 mini-chocolate chips for eyes.