If you try hard enough, you can almost convince yourself that this is healthy because of the plums.
Preheat oven to 400F. Melt 2 tablespoons butter in large ovenproof skillet over medium heat. Add 2 tablespoons brown sugar and wine. Bring just to a boil, stirring until sugar dissolves and syrup is smooth; remove skillet from heat.
Whisk remaining 3 tablespoons brown sugar, flour, 3 tablespoons of sugar and salt in medium bowl to blend. Add remaining 3 tablespoons of butter. Cut in with back of fork until streusel begins to hold together. Mix in nuts.
Cut very thin slice off rounded side of each plum half (to create flat surface). Lightly press 1 tablespoon onto cut side of plum half. Place plums streusel side up, in syrup in skillet.
Roast plums until just tender, about 20 minutes. Remove skillet from oven and preheat broiler. Remove skillet from oven and preheat broiler. Broil plums until streusel is crisp and golden, about 1-½ minutes. Place 2 plum halves in each of 6 large goblets. Top with ice cream, then spoon over syrup from skillet.