Hasselback-style potatoes au gratin with bacon, caramelized onion and three cheeses

Render the very finely diced bacon without oil; about halfway, after about two minutes, add the onion with a squeeze of oil and cook 10 to 15 minutes, stirring now and then, until caramelized.

Slice the peeled potatoes about an eighth of an inch thick on a mandolin, returning the slices to water so they do not brown.

Grate and weigh the cheeses: two ounces smoked gruyere, two ounces fontina, one ounce parmesan; mix, holding a little back for the top.

In a bowl combine most of the cheese, two cups heavy cream, the bacon and onion, a squeezed head of roasted garlic, fresh thyme and a big pinch of salt and pepper.

Dry the potato slices on a towel, then add them to the bowl in small stacks so the sauce gets between them.

Stand stacks of slices on edge around the dish, hasselback style, pour in the remaining liquid to about halfway up, and wipe the edges.

Cover tightly with foil and bake at 400 about 35 to 40 minutes; uncover for about 15 more, then top with the reserved cheese for another 10.

Add the reserved cheese and bake until bubbling.

Rest 10 minutes before eating; finish with finely chopped chives.