In a small bowl, combine the first 6 ingredients. Cut in butter until mixture resembles coarse crumbs. Combine egg substitute and 1/4 cup nectar; stir into the flour mixture just until moistened.
Coarsely chop mango slices; combine with marmalade, lemon juice and remaining nectar.
Transfer to an 8-in. cast-iron or other ovenproof skillet; stir in raisins. Bring to a boil. Drop flour mixture in 8 mounds onto the simmering mango mixture. Reduce heat; cover and simmer until a toothpick inserted in a dumpling comes out clean, 12-15 minutes (do not lift the cover while simmering). Sprinkle with ginger and almonds; if desired, serve with frozen yogurt.