Heat the oven to 350°F and generously grease a standard 12-cup muffin pan, paying special attention to the sides and the area around the rims.

Separate the biscuits and cut each biscuit into 6 pieces, creating about 48 small dough pieces.

Mix the granulated sugar and cinnamon in a resealable bag or bowl. Add the biscuit pieces in batches and toss until every piece is well coated.

Place 3 to 4 coated dough pieces into each prepared muffin cup, adding chopped pecans or walnuts between the pieces if desired.

Stir the melted butter and packed brown sugar together until combined, then spoon or pour the mixture evenly over the dough pieces.

Bake for 18 to 25 minutes, until the muffins are puffed and browned and the centers are cooked through.

Let the muffins stand for about 5 minutes, then carefully invert the pan onto a tray or serve the muffins individually. Drizzle with powdered sugar glaze if desired.