Basic Yam (Sweet Potato) Puff

This is a simpler (and closer to the original) version of the Spiced Sweet Potato Puff recipe I posted previously.

4 large yams (sweet potatoes, the dark orange kind)

¼ cup butter

2 well-beaten eggs

⅓ cup sugar

¼ tsp baking soda

1 tsp. salt

Pare potatoes and boil until tender, then drain--or, for a richer flavor, bake them in the skins and then peel them. Mash and add remaining ingredients. Beat well and transfer to buttered casserole. Dot with additional butter and bake in moderate oven (350 degrees) for 30-40 minutes.