Preheat oven to 350F. Add prepped potatoes to a saucepan. Cover with water and bring to a boil. Boil for 10 minutes; drain. Transfer drained potatoes to a greased 8x11-inch pan.
In a medium saucepan, melt the butter over medium heat. Whisk in the flour and cook, stirring constantly, until lightly browned, 2 to 3 minutes. Whisking constantly, slowly pour in the heavy cream and milk until the sauce is smooth. Stir in half of the gruyère, salt, and Garlic Galore Seasoning. Cook, whisking gently, until the cheese is melted.
Pour the sauce over the potatoes in the baking dish. Give a gentle stir to be sure all the potatoes are coated in sauce. Top with the remaining gruyere cheese.
Bake for 15 minutes. Turn the broiler to high and broil for 5 minutes more, or until golden brown. Top with fresh herbs such as chives or parsley.
