Preheat oven to 325 degrees F.

Coat a 9x6x3-inch casserole with cooking spray.

Finely chop sweet potatoes to texture of large rice in several batches in food processor, pulsing machine on and off (or finely grate by hand).

Combine sweet potatoes, brown sugars, salt, ginger and cornmeal in large mixing bowl. Stir in egg, egg yolks, cream and vanilla.

Transfer to casserole. Bake for 15 minutes.

Stir from outside to middle. Bake 10 minutes longer; stir again.

Bake until lightly browned and just set, about 15 to 25 minutes longer (for a total of about 40 to 50 minutes).

Serve hot or at room temperature, plain or topped with cream.