In a medium bowl, stir together sweet potato and banana. Add milk, blending well.
Add brown sugar, egg yolks, and salt, mixing thoroughly.
Spray a 1-quart casserole with nonstick cooking spray. Transfer sweet potato mixture to casserole dish.
Combine raisins, sugar, and cinnamon; sprinkle over top of sweet potato mixture.
Bake in a preheated 325º F oven for 40-45 minutes or until a knife inserted near center comes out clean. Than ready to serve