Recipe - Potato Onion And Rosemary Cake

2 tablespoon Unsalted butter
2 tablespoon Olive oil
1 One half pound Onions; thinly cut or sliced up
2 pound Small red potatoes; peeled,
and
Thinly cut or sliced up
One half teaspoon Salt
1 teaspoon Freshlyground black pepper
2 tablespoon Coarselychopped fresh
rosemary
1 cup Cream; whisked together
With
1 lg Egg yolk

In a large heavy skillet heat the butter and olive oil over low heat. Saute
the onions slowly, stirring occasionally, for about 30 minutes. They should
be very soft, slightly golden, but not brown. Preheat the oven to 350
degrees. Lightly oil a 10inch round baking dish or pie plate. Arrange a
circular layer of overlapping potatoes in the pan and sprinkle with salt
and pepper. Arrange a thin layer of onions on top and sprinkle with some of
the rosemary. Continue layering until you have used up all the ingredients,
finishing with the rosemary. Pour the cream mixture into the dish around
the edges so that you don't disturb the rosemary, drizzling just a little
over the top. Cover the pan with aluminum foil and bake for 40 minutes.
Remove the foil and cook for 10 minutes more, until the top is golden and
the potatoes are tender. Let cool for 5 minutes then slice into loose
wedges and serve. This recipe yields 8