Preheat oven to 400°F. Wash beets then wrap in parchment-lined aluminum foil and roast in center of oven until tender, 45 to 60 minutes. Cool, then peel and halve.
Meanwhile, whisk together shallots, lemon juice and mustard. Whisk in oil until emulsified and season with salt and pepper. Add beets and toss gently to coat. Arrange spinach on a large platter. Using a slotted spoon, transfer beets to plates, arranging them on top of the spinach. Top with cheese, drizzle lightly with some of the remaining dressing and serve, with more dressing on the side, if you like.
Per Serving:190 calories (15 from fat), 15g total fat, 5g saturated fat, 15mg cholesterol, 420mg sodium, 10g carbohydrates, (2 g dietary fiber, 6g sugar), 6g protein.