Potatoes Au Gratin

INGREDIENTS

1/4 cup

unsalted butter ((60g, 2 ounces))

1 tbsp

minced garlic ((8g))

1/2 cup

finely chopped yellow onion ((72g))

1/4 cup

all-purpose flour ((30g, 1 ounce))

2 cups

whole milk ((480 ml))

3/4 tsp

kosher salt ((4g))

1/2 tsp

black pepper

1/8 tsp

nutmeg

2 lb

yukon gold potatoes ((908g) peeled and cut into 1/8-inch thick slices)

1 cup

shredded gruyere cheese ((117g, 4 ounces))

1 cup

shredded sharp cheddar cheese ((117g, 4 ounces))

2 tsp

chopped chives ((1g))