Boil potatoes in water to cover by 1 inch until tender. About 20 minutes.
Heat half-and-half, butter, garlic, mustard, and salt over medium low heat until smooth. About 5 minutes. Remove from heat and keep warm.
Drain potatoes and transfer to mixing bowl. Mix using an electric mixer on medium-low and slowly add half-and-half mixture until potatoes are smooth and creamy, about 2 minutes.
Add eggs 1 at a time until mixed well, about another minute.
Fold in chives.
Transfer to greased 2-quart baking dish. Make a nice little design in the top of the potatoes with a fork.
The dish may be covered and refrigerated for up to 24 hours - If so,let it sit at room temp for an hour before continuing.
Bake at 375 degrees until potatoes begin to brown.