Place an oven rack about 6 inches below heater element and preheat broiler. Mix together sugar and cinnamon in a small bowl and set aside.
Place biscuits on a foil-lined sheet pan or baking dish and spread tops with Challenge Spreadable Butter. Sprinkle each biscuit with a generous teaspoon of cinnamon-sugar mixture. Broil for about 2 minutes, watching closely, until butter melts into the biscuit and sugar begins to caramelize.
Remove pan from oven and carefully flip biscuits. Spread bare sides with remaining butter and sprinkle with cinnamon-sugar mixture. Broil another 2 minutes or until top is caramelized and crisp.
Serve in a bowl with warm milk.