Vegetable Stacks - cooking recipe

Ingredients

1/2 cup olive oil
1 large eggplant, cut in 12 slices (1/2 inch thick)
3 medium zucchini, cut in 24 slices (1/4 inch thick)
3 medium red onions, cut in 12 slices (1/3 inch thick)
2 large tomatoes, cut in 6 slices (1/2 inch thick)
3/4 cup ricotta cheese
salt and pepper
2 teaspoons fresh thyme, chopped
1/2 lb mozzarella cheese, cut in 6 slices (1/4 inch thick)
6 sprigs fresh rosemary

Preparation

Preheat BBQ and set on LOW. Brush vegetables with olive oil, season with salt and pepper, and grill slowly until tender, turning once. They will only need about 3-4 minutes per side. Transfer the vegetables to a tray, arranging them in a single layer, and cover tightly with plastic wrap. You can stack layers of the vegetables on top of each other with a layer of plastic wrap between; just be sure the vegetables have cooled first. The vegetables may be grilled a day in advance, and refrigerated after cooking. Bring the vegetables back to room temp before proceeding.
Stir together the ricotta, thyme, salt and pepper in a small bowl.
Place one slice of eggplant on a lightly oiled baking sheet or foil pan. Spread one tablespoon of the ricotta mixture over the eggplant. Cover with 2 slices of zucchini, 1 slice of onion, 1 slice of mozzarella, 1 slice of tomato, 2 slices of zucchini, and 1 slice of onion. Spread 1 tablespoon of the ricotta mixture over the onion, and top with another slice of eggplant. Repeat this procedure with the remaining vegetables to make 5 more stacks.
Insert a wooden skewer through the centre of each stack to create a hole from top to bottom. Remove the bottom leaves from each rosemary sprig, leaving one inch of leaves on the top. Insert 1 sprig into the centre hole in each stack and return to the BBQ. Heat for about 5 minutes on Low or until mozzarella is melted and vegetables are warmed through.