Ingredients
FOR THE POTATOES
1 pound Yukon gold potatoes, peeled and cut into 1 1/2-inch pieces 3/4 pound russet potatoes, peeled and cut into 1 1/2-inch pieces
4 garlic cloves
1/2 cup nonfat milk
2 tablespoons unsalted butter
1/4 teaspoon coarse salt
Freshly ground pepper
FOR THE FILLING
2 teaspoons olive oil
1 large shallot, minced (about 1/4 cup)
10 ounces button mushrooms, quartered
1/4 teaspoon coarse salt
2 teaspoons chopped fresh flat-leaf parsley
2 teaspoons chopped fresh thyme
1 1/2 cups homemade or low-sodium canned chicken stock, skimmed of fat
2 cups plus 1 tablespoon cold water
1 dried bay leaf
4 small leeks (about 1 1/4 pounds), white and light-green parts, cut into 1/8-inch rounds, washed thoroughly and drained
1 whole boneless and skinless chicken breast (about 1 1/8 pounds), cut into 1-inch pieces
1/2 pound shelled fresh or frozen peas
1 teaspoon cornstarch
Instructions
Make the potatoes: Place potatoes and garlic in a medium saucepan. Cover with cold water; bring to a boil over high heat. Reduce heat to a bare simmer; cook until potatoes are easily pierced with a fork, about 15 minutes. Drain; pass through a food mill into a large bowl. In the same pan, heat milk, butter, and the salt. Pour over potatoes; stir to combine. Season with pepper; cover, and keep warm.
Make the filling: Heat broiler with rack in lowest position. In a medium saute pan, heat the oil over medium heat, and add shallot. Cook until soft, about 3 minutes. Stir in the mushrooms and the salt. Cook, stirring occasionally, until lightly golden and beginning to soften, about 8 minutes. Add parsley and thyme; remove from heat. Divide evenly among four 2-cup ovenproof dishes.
Bring stock, 2 cups water, and bay leaf to a boil in a medium saucepan; add leeks and chicken. Reduce heat to medium; simmer until chicken is cooked through, about 4 minutes. Add peas; immediately turn off heat. Using a slotted spoon, divide chicken mixture evenly among baking dishes. Reserve 1 cup cooking liquid in saucepan; set aside remainder for another use (store in an airtight container in refrigerator up to 2 days).
In a small bowl, combine cornstarch with about 1 tablespoon water; whisk until smooth. Slowly whisk into reserved broth in saucepan, and bring to a simmer over medium heat. Cook 1 minute, and ladle into baking dishes, dividing evenly. Spoon about 1 cup potato mixture on top of each dish, and place under broiler until tops begin to brown, 10 to 12 minutes. Remove from broiler, and serve hot.
