In a medium sauce pan melt the butter and sauté the onion and the garlic.
Add milk and simmer over low heat.
After boiling turn off the heat and add the heavy cream.
Add the salt, pepper and nutmeg and set aside.
In a deep dish of approximately 40 cm in length, set the dish by creating layers of the sauce, cheese and slices of Anauá yam. Top with sauce and cheese.
Bake for about 40 minutes or until yamis tender and Golden brown. Serve immediately.