Two Potato Gratin with Horseradish Crust

Topping Ingredients:

• 1 1/2 - 2 cups coarse fresh bread crumbs (from ciabatta or similar bread)
• 2 TBS butter, melted
• 1 TBS Dijon mustard
• 2 TBS grated Parmigiano or Asiago cheese

Gratin Ingredients:

• 2 TBS butter, melted
• 1 cup thinly sliced shallots (6 to 7 large shallots)
• Salt and freshly ground pepper to taste
• 2/3 cup heavy cream
• 2/3 cup low sodium chicken broth
• 2 TBS prepared horseradish
• 1 russet potato (large - 12 oz)
• 1 sweet potato (large - 12 oz)
• 1/3 cup grated Parmesan or Asiago cheese

Make topping: Combine breadcrumbs, melted butter, mustard and cheese. Set aside.

Prepare gratin: Preheat oven to 350 degrees. Butter a shallow 2 quart gratin dish. Melt 2 TBS butter in small saucepan over medium heat. Add shallots, and a pinch of salt. Cook shallots, stirring frequently, until limp and somewhat golden. Whisk together the cream, chicken broth, and horseradish. Add to shallots, season with salt and pepper, and remove from heat.

Peel the potatoes, cut each in half lengthwise, and slice each across into thin half moons. In a large bowl, combine the potato slices, cheese, and the shallot cream mixture. Using a spatula, combine all ingredients gently, and scrape into prepared dish, smoothing to evenly distribute. Cover with crumb topping.

Bake until the crust is golden brown, and potatoes are tender when pierced with a fork, about 1 hour (may take up to 15 additional minutes). Let rest 15-20 minutes before serving. 8 servings.

Make-ahead tips: To prepare ahead of time, make breadcrumbs and grate cheese, but do not combine topping ingredients until ready to bake. Gratin ingredients can be assembled and refrigerated, covered, for several hours. Remove casserole from refrigerator for 45 minutes prior to baking. When ready to bake, combine topping ingredients, add to gratin, and bake as directed. From ?Fine Cooking?, October 2003.