Mashed Potato Casserole

1 . Stage

In a medium saucepan over medium heat, bring milk, thyme, bay leaves, 4 tablespoons butter, 1/2 teaspoon salt, and 1/4 teaspoon pepper to a simmer. Remove from heat, cover, and let stand 1 hour.

2 . Stage

Preheat oven to 375°. Grease a 2 1/2- to 3-quart baking dish with butter.

3 . Stage

In a large pot, combine potatoes and garlic. Cover with at least 2" water; season with 2 tablespoons salt. Bring to a boil and cook until fork-tender, 12 to 15 minutes. Reserve 3/4 cup cooking liquid, then drain. Return potatoes and garlic to pot and mash with a potato masher until smooth.

4 . Stage

Meanwhile, return infused milk to a bare simmer over medium heat; discard thyme and bay leaves. Add cream cheese and 1/4 cup Parmesan and stir until smooth and melted. Add to mashed potatoes along with eggs. If needed, gradually add reserved cooking liquid until consistency is thick but spreadable; season with salt and pepper. Transfer mixture to prepared dish.

5 . Stage

In a small skillet over medium heat, melt remaining 2 tablespoons butter. Cook, swirling pan, until butter begins to brown and smell nutty, 2 to 3 minutes. Remove from heat and stir in panko and remaining 1/4 cup Parmesan; season with salt and pepper. Sprinkle over mashed potato mixture. Cover pan with foil.

6 . Stage

Bake casserole 10 minutes. Uncover and continue to bake until hot and topping is golden brown, 20 to 22 minutes. Top with chives.