Mashed Potato Casserole

3 pounds russet potatoes, peeled and cut into 1-inch pieces
1/2 cup half-and-half
1/3 cup chicken broth
8 tablespoons unsalted butter, cut into pieces
1 small garlic clove, minced
1 1/2 teaspoons Dijon mustard
1 1/2 teaspoons salt
3 large eggs
2 tablespoons finely chopped chives

1.  Place potatoes in large pot and cover with 1 inch cold water.  Bring to boil over high heat, then reduce heat to medium and simmer until potatoes break apart when knife is inserted, about 20 minutes.

2.  Heat half-and-half, broth, butter, garlic, mustard, and salt in saucepan over medium-low heat until butter is melted, about 5 minutes.  Stir until mixture is smooth, then remove from heat and cover to keep warm.

3.  Drain potatoes and transfer to bowl of stand mixer fitted with paddle; mix on medium-low speed, slowly adding half-and-half mixture, until smooth, about 1 minute.  Beat in eggs, one at a time, until incorporated, about 1 minute,  Fold in chives.

4.  Transfer potato mixture to greased 2-quart baking dish and use fork to make peaked design on top.

5.  TO STORE:  Cover casserole with plastic wrap, taking care not to flatten peaks, and refrigerate for up to 24 hours.

6.  TO SERVE:  Let casserole sit at room temperature for 1 hour before baking.  Adjust oven rack to upper-middle position and heat oven to 375F.  Bake until potatoes rise and begin to brown, about 45 minutes.  Let cool for 10 minutes before serving.