Preheat the oven to 375 degrees F. Grease a 6-cup muffin tin with nonstick spray.
Lay the biscuits flat on a microwave-safe plate and microwave at 30 percent power in 30-second increments until thawed, flipping biscuits over after each increment. Thawing will take 4 to 5 times total. Alternately, you can leave the biscuits at room temperature (covered) until they are thawed out.
In a small bowl, combine the granulated sugar and cinnamon.
Use scissors to cut each biscuit into eight even pieces. Dip each piece first in the butter, and then toss in the cinnamon sugar to coat completely. Put nine pieces in each muffin cup and bake until golden brown and centers are set, 16 to 18 minutes.
While the muffins bake, in a small bowl, combine the powdered sugar and milk and whisk together until smooth to form a glaze. Drizzle the glaze over the baked muffins and serve immediately.