Step 1Place the wine and cranberries in a small bowl. Microwave until slightly warm, about 30 seconds. Let stand for 1 hour.
Step 2Heat 1 tablespoon of the butter in a medium nonstick skillet over medium-high heat. When hot, stir in the onions. Place foil or wax paper close to the onions to "sweat" them, or cover with a lid. Cook, stirring often, until lightly browned, about 5 minutes. Stir in the sugar. Cook 1 minute longer; do not allow the onions to burn, but it's OK if they're dark brown. Add the cranberries and wine along with the broth. Gently simmer, uncovered, until the onions are slightly softened (but not mushy), stirring often and adding more broth or a little water if the mixture becomes too dry, about 7 minutes. (This can be made a day ahead to this point and refrigerated. To serve, gently reheat.)
Step 3Add the skimmed pan juices, brandy and remaining tablespoon of butter, stirring until the butter is melted. Season with the salt and pepper. Taste; adjust the seasoning. Serve hot, spooned over sliced pork roast.