With layers of soft, buttery leeks and tender-crisp kohlrabi, this is not your grandma's gratin--it's better. Use a mandoline for the most even slices of kohlrabi. Serve this healthy side dish in place of potato gratin with roast chicken or pork for a satisfying dinner.
To make ahead: Prepare through Step 5; cover and refrigerate for up to 1 day.
2 1/2 vegetable, 1/2 fat, 1/2 high-fat protein, 1/2 starch