1. Preheat oven to 375°.
2. Leave root and 1 inch stem on beets; scrub with a brush. Reserve beet greens. Wrap beets and 2 tablespoons water in foil. Bake at 375° for 1 hour or until tender. Trim off beet roots; rub off skins. Cut beets into 1/4-inch slices.
3. Cook reserved greens in boiling water 2 minutes; drain. Rinse with cold water; drain and pat dry. Coarsely chop, reserving 3/4 cup greens; reserve remaining greens for another use.
4. Arrange half of beets in a single layer in an 11 x 7–inch baking dish coated with cooking spray. Sprinkle with half the cheese, black pepper, salt, and sherry vinegar. Repeat procedure with remaining beets, cheese, black pepper, salt, and sherry vinegar. Spread greens evenly on top of beet mixture. Pour half-and-half evenly over greens; top evenly with panko. Bake at 375° for 25 minutes or until beets are tender.