Notes: If making ahead, chill airtight up to 1 month. Reheat to soften. The caramel powder mixture (through step 4) is fluffier than sugar, so you get more than you start with.
1. Line a 10- by 15-inch pan with foil.
2. In a 10- to 12-inch nonstick frying pan over medium-high heat, shake sugar often until melted and amber-colored, 8 to 10 minutes.
3. Pour melted sugar onto foil. Let stand until hard, about 30 minutes. Peel off foil and break caramel into chunks.
4. With motor running, drop chunks into a food processor and whirl into a fine powder. Or whirl chunks in batches in a blender.
5. In a 6- to 8-quart pan, bring cream and caramel powder to a rolling boil, stirring (powder lumps, then melts). Serve warm or cool.
Nutritional analysis per tablespoon.