Slice cheese into 3/4" slices and arrange in a shallow dish. Combine the oil and the fresh thyme and pour over the cheese. Marinate for several hours.
Preheat oven to 400 degrees F. Trim all but 1-inch off the stems of the beets. Wash the beets well. Brush the beets with olive oil, sprinkle with salt and pepper and wrap in tin foil. Place the beets in a shallow baking pan and roast until a skewer inserted into the beets comes out easily, about 45 minutes to 1 hour (possibly more depending on the size of the beets).
Remove the beets from the oven and carefully open the packets. When the beets are cool enough to handle, carefully remove the skins from the beets and dice. Toss gently with some of the vinaigrette and set aside.
Meanwhile, turn down the oven to 350 degrees F. Mix the bread crumbs, dried thyme, salt and pepper in a shallow bowl. Dip each goat cheese round in the breadcrumb mixture to coat and place in a baking dish. Bake for 15 minutes or until the cheese is softened and crumbs are golden.
Toss the greens with vinaigrette. Arrange salad on individual plates with beets and one to two rounds of goat cheese.