Baked Marshmallow Sweet Potatoes

2 lbs ( about 6) fresh sweet potatoes or yams, or 2 - 1lb. cans of sweet potatoes or yams 
1 cup sour cream - regular or lite 
2 egg yolks 
1 tsp. salt 
1-1/2 cups miniature marshmallows

Preparation of the baked marshmallow sweet potatoes.
Place fresh sweet potatoes in a large saucepan, add water to cover and bring to a low boil. 
Cook, covered, for about 30 minutes or until fork tender. Drain off the water and remove the skin. 
Place the cooked (or canned) sweet potatoes in a food processor. 
Add the sour cream, egg yolks and salt; process until smooth and well blended. 
Pour the mixture into a buttered casserole dish. Top with the mini marshmallows. Bake at 350º for 30 minutes or until the marshmallows are puffy and lightly browned on top.