Chicken with Slow-Roasted Tomatoes and Cheesy Grits

Preheat oven to 350 degrees F. On a rimmed baking sheet, toss tomatoes with 2 tablespoons oil and season with salt and pepper. Turn tomatoes cut side down and scatter rosemary around; bake on bottom shelf of oven for 1 hour and 15 minutes, or until very soft and starting to brown. Let cool, then discard skins. Meanwhile, in a roasting pan, rub chicken all over with 1 tablespoon oil and season with salt and pepper. Scatter onion wedges around chicken, drizzle with remaining 1 tablespoon oil, and season with salt and pepper. Roast chicken and onions in upper third of oven for 1 hour and 10 minutes. Increase oven temperature to 450 degrees F. Add wine to pan and roast chicken about 20 minutes longer, until onions are well browned and chicken is golden and cavity juices run clear. Pour cavity juices into pan. Transfer chicken and onions to a platter; let chicken rest 10 minutes. Set roasting pan over moderately high heat and add 4 tomato halves and 1/2 cup water. Simmer, scraping up any browned bits and mashing tomatoes, until reduced by one-third. Strain jus into a saucepan and season with salt and pepper. Carve chicken and serve with tomatoes, onions, tomato jus, and Creamy Cheese Grits.