Scrub potatoes; remove eyes and/or sprouts. In a covered large saucepan, cook potatoes in enough boiling water to cover about 25 minutes or until tender, adding the carrot pieces for the last 4 minutes of cooking time. Drain; cool until easy to handle. Very thinly slice potatoes and carrots, keeping the carrots separate from the potatoes.

Preheat oven to 400 degrees F. Line a 9x1-1/2-inch round baking pan with heavy foil. Generously coat foil with cooking spray. Layer half of the beet slices, half of the carrot slices, half of the zucchini slices, and half of the potato slices in pan. Drizzle with olive oil and sprinkle with half of the salt and half of the pepper. Layer remaining vegetable slices on top. Sprinkle with the remaining salt and pepper. Cover with foil; press down lightly with hands.

Bake for 30 to 35 minutes or until vegetables are tender. Let stand for 5 minutes. Remove top piece of foil. Invert vegetables onto serving plate; peel off foil. Cut into 8 wedges to serve.

Using a mandolin will allow you to cut the vegetables into very thin slices.