Directions

1. Place potatoes in a large stockpot or Dutch oven; cover with cold salted water. Bring to a boil; reduce heat, cover and simmer until potatoes are tender, about 5 minutes. Drain well; set aside.
2. Preheat oven to 375 degrees F. Lightly oil a 9 x 13 baking dish or coat with nonstick spray.
3. Melt butter in a Dutch oven over medium heat. Add garlic and shallot, and cook, stirring frequently, until tender, about 3-4 minutes.
4. Whisk in flour until lightly browned, about 1 minute. Gradually whisk in chicken stock and heavy cream. Bring to a boil; reduce heat and simmer, stirring constantly, until reduced and thickened, about 5 minutes.
5. Remove from heat; stir in 3/4 cup white cheddar cheese and mustard. Stir in potatoes; season with salt and pepper, to taste.
6. Spread potato mixture into the prepared baking dish. Place into oven and bake until potatoes are tender and mixture has thickened, about 35-40 minutes.
7. Sprinkle with remaining 1 1/4 cups white cheddar cheese. Place into oven and broil until golden brown, about 3 minutes. Let stand 5 minutes.
8. Serve immediately, garnished with chives, if desired.