Rinse the black-eyed peas with cold running water and discard any stones or shriveled peas. Into a 6-quart Dutch oven, place the peas, bay leaf and enough water to cover, and heat to boiling over high heat. Reduce heat to low. Cover and simmer for 30 to 40 minutes or until peas are almost tender. Drain peas, keeping 2 cups of the liquid. Discard bay leaf. (Can be done up to 2 days ahead to this point. Refrigerate until ready to proceed with recipe.).
Saute onion in olive oil, over medium heat, until partially cooked and translucent, 5-6 minutes.
Preheat oven to 350°F Empty peas into a 4-quart baking dish and add all remaining ingredients (including onions and reserved bean water). Stir to distribute ingredients evenly throughout casserole. Taste some of liquid and season with salt and pepper to taste.
Bake for 40-50 minutes, or until hot and bubbly. The casserole will be quite 'wet' and should be served in bowls. Even better the next day.