Sweet Potato with Milk in the Oven

Boil the peeled sweet potatoes in water and salt until they are slightly tender

Don't overcook them

Drain the cooked sweet potatoes and cut them into slices

Arrange them carefully on a baking dish greased with corn oil

Prepare a separate sauce in a small saucepan over low heat by whisking together milk, salt, and cornstarch that has been previously dissolved and mixed with egg yolk

Whisk continuously until the sauce thickens

Remove from heat, add grated Parmesan cheese, and pour the sauce over the sweet potatoes

Place in a hot oven, preheated to bake, and gratinate

Serve with roast beef.