Preheat oven to 375 degrees. Butter, oil or spray two small baking dishes with cooking spray.
Place potatoes and garlic in a small saucepan. Add heavy cream or half-and-half and salt and white pepper to taste.
Bring to a simmer and gently cook the potatoes for 4 minutes. Remove potatoes and garlic to a plate with a slotted spoon.
Whisk grated cheese into cream until smooth.
Layer ⅓ of the potatoes into the two individual baking dishes (⅙ into each dish). Drizzle both dishes with ⅓ of the cheese sauce. Repeat layering two more times, finishing with cheese sauce.
Place on a baking sheet, cover with aluminum foil and bake for 35-40 minutes or until the potatoes are tender and gratins are bubbling.
If using half-and-half, whisk in 1 tablespoon all-purpose flour.MAKE AHEAD: Can be prepared up to the point of baking 1-2 days ahead of time. Let sit out at room temperature while the oven preheats. You may need to add additional baking time.