Preheat oven to 375 °F (190 °C). Spray a 6‑cup muffin tin well with nonstick spray.

In a small bowl, combine sugar and cinnamon; set aside.

Open croissant dough and separate into triangles. Brush each triangle with melted butter, then generously sprinkle with cinnamon sugar.

Roll each triangle up from the wide end to the tip, twisting slightly as you roll to get those flaky layers.

Place each roll into a muffin cup, tip side down, and press into the bottom.

Once the tin is full, bake for 15–18 minutes until golden brown and crispy.

Let cruffins cool in the pan for 5 minutes, then transfer to a wire rack to cool completely.

Meanwhile, whisk together powdered sugar, milk, and vanilla until smooth. Adjust thickness to desired drizzle consistency.

Drizzle glaze over cooled cruffins and allow it to set for a few minutes before serving warm or at room temperature.