1. Preheat your oven and prepare your muffin tin: Set your oven to 375 F (190 C). Lightly grease a 12-cup standard muffin tin with cooking spray or butter. This prevents sticking and ensures easy removal of your muffins.

2. Combine the cinnamon sugar: In a medium-sized shallow bowl, whisk together the granulated sugar and ground cinnamon until they are thoroughly combined. This creates your delicious coating for the biscuit pieces.

3. Prepare the biscuit dough: Open the can of refrigerated biscuit dough. Separate each biscuit and cut each one into 4-6 smaller pieces. You can use a knife or kitchen shears for this. The goal is to have bite-sized chunks that will bake up nicely in the muffin tin.

4. Coat the biscuit pieces: In a separate small bowl, melt the unsalted butter. Dip each biscuit piece into the melted butter, ensuring it’s fully coated, then immediately transfer it to the cinnamon sugar mixture. Toss gently to coat each piece completely.

5. Arrange in the muffin tin: Place 3-4 coated biscuit pieces into each prepared muffin cup. Don’t worry if they look a little loose; they will expand and meld together as they bake.

6. Bake until golden brown: Place the muffin tin in the preheated oven and bake for 15-20 minutes, or until the muffins are puffed up, golden brown, and cooked through. A toothpick inserted into the center should come out clean.

7. Cool slightly and serve: Once baked, remove the muffin tin from the oven. Let the muffins cool in the tin for about 5 minutes before carefully removing them to a wire rack. This helps them set and prevents them from breaking apart. Serve warm and enjoy!