Can I make this potato gratin ahead of time?
Yes. Assemble the dish completely, cover with foil, and refrigerate up to 24 hours. Add 10–15 minutes to the bake time if starting from cold.
How do I know when the potatoes are fully cooked?
The potatoes should be fork-tender and the top should be golden brown. The cream sauce will thicken as it bakes and may bubble slightly at the edges.
Can I substitute the sharp cheddar cheese?
Yes. Gruyère, aged Emmental, or smoked gouda work well. Avoid pre-shredded cheese as it contains anti-caking agents and won't melt as smoothly.
What's the purpose of roasting the garlic first?
Roasting mellows garlic's sharpness and makes it sweet and creamy. Raw garlic would overpower the dish and could taste harsh.
Can I scale this recipe up for a larger crowd?
Yes. Double all ingredients and use a 9×13-inch baking dish or larger. Increase bake time by 10–15 minutes, checking that potatoes are tender and top is golden.