In a large saucepan, combine the potatoes with enough cold water to cover by 1 inch. Bring to a boil over high heat, reduce the heat and simmer actively for about 10 minutes, or until the potatoes are just tender. Remove from the heat, drain and, when cool enough to handle, slice the potatoes 1/8inch thick.
While the potatoes are cooking, in a large heavy skillet, heat the butter and olive oil over medium heat. Add the onions and saute, stirring occasionally, for 4 to 5 minutes, or until softened. Stir in 1 teaspoon salt and 1/2 teaspoon black pepper and remove from the heat.
Preheat the oven to 425/. In a small bowl, combine the garlic and herbs and toss together to mix evenly. Brush a large oval or rectangular baking dish with a little olive oil and place one layer of sliced potatoes, slightly overlapping, in the bottom. Distribute about 1/4 of the sliced onions
evenly over the potatoes, then scatter a little of the garlic-herb mixture over the top and drizzle with a little olive oil. Make another layer of potatoes and repeat until all the potatoes, onions, and garlic mixture have been used up, finishing with a layer of the olive oil and herb mixture.
Pour the chicken stock around the edges of the pan so as not to disturb the herb topping, and cover with aluminum foil. Bake on the lower middle shelf of the oven for about 30 minutes,until the potatoes are perfectly tender. Remove the foil and cook for 5 to 10 minutes more, until the top is slightly dried. If desired, scatter the cheese over the top after removing the foil. Serve warm.
c.1997, M.S. Milliken & S. Feniger, all rights reserved