1. Cook the beans: Using a sharp knife, slice off stem end of onion, and score shallow slits all over, making sure it stays intact. Place in a large saucepan with the bay leaf and the peppercorns; fill with enough water to just cover (about 3 quarts). Bring to a boil; reduce heat, and simmer 20 minutes. Add beans; simmer until cooked through, about 15 minutes.

2. Drain beans, reserving cooking liquid. In a medium bowl, toss beans with 1 tablespoon each oil and cooking liquid; season with salt and pepper. Set aside.

3. Cook bacon in large skillet over medium heat until crisp. Transfer to paper towels to drain. Pour off all but 2 tablespoons rendered bacon fat, and return the skillet to medium heat. Working in batches if necessary, saute squash until cooked through and golden, about 10 minutes. Season with salt and pepper, and transfer to a bowl; set aside.

4. Heat 3 tablespoons oil in the same skillet over medium heat. Add garlic, and saute until just golden, 1 to 2 minutes. Add broccoli rabe; saute until wilted and heated through, about 5 minutes. Season with salt and pepper.

5. Add beans and squash to skillet, and cook just until heated through. Drizzle with remaining tablespoon oil, and season with salt and pepper. Sprinkle reserved bacon on top, and serve.