Mashed Potato Casserole
- 4 Pounds russet potatoes
- 1/2 Cup half-and-half
- 1/2 Cup low-sodium chicken broth
- 1 garlic clove
- 2 Teaspoons Dijon mustard
- 2 Teaspoons table salt
- 4 large eggs
- 1/4 Cup finely chopped fresh chives
- 12 Tablespoons (1 1/2 sticks) unsalted butter
Peel and cut 4 pounds russet potatoes into 1-inch chunks. Cut 12 tablespoons unsalted butter into pieces. Peel and mince 1 garlic clove. Finely chop enough fresh chives to yield ¼ cup.
Cook Potatoes and Heat Dairy Mixture
Add potatoes to Dutch oven or large pot and add water to cover by 1 inch. Bring potatoes and water to boil over high heat. Reduce heat to medium and simmer until potatoes are tender, about 20 minutes. Place ½ cup half-and-half, ½ cup low-sodium chicken broth, butter, garlic, 2 teaspoons Dijon mustard, and 2 teaspoons table salt in small saucepan. Warm dairy mixture over medium-low heat until smooth, about 5 minutes. Keep warm.
Drain potatoes in colander 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 4 large eggs one at a time until incorporated, about 1 minute. Fold in chives. Transfer potato mixture to greased 3-quart baking dish and use fork to create deep ridges on top. Cover baking dish with plastic wrap and refrigerate for up to 24 hours. (Casserole can be baked right away; if doing so, reduce baking time in step 18 to 35 minutes.)
Let casserole sit at room temperature for 1 hour. Adjust oven rack to upper-middle position and heat oven to 375 degrees. Bake until potatoes rise and begin to brown, about 45 minutes. Let cool 10 minutes. Serve