1 chicken, about 4 1/2 pounds, cut into 8 pieces, back and wings discarded
Kosher salt and freshly ground black pepper, to taste
2 tablespoons plus 1/3 cup extra-virgin olive oil
1 large yellow onion, chopped
10 garlic cloves, peeled
1/2 cup dry white wine
1 1/2 cups chicken broth
4 fresh sage sprigs, plus 2 tablespoons finely chopped sage
3 1/2 pounds Early Girl tomatoes, cored
Season the chicken with salt and pepper. In the stovetop-safe insert of a slow cooker over medium-high heat, warm the 2 tablespoons olive oil. Add the chicken, skin side down, and brown, turning once, 7-8 minutes total. Transfer to a plate.
Add the onion to the insert, reduce the heat to medium, and cook, stirring occasionally, until softened and golden, about 8 minutes. Add the garlic and cook, stirring occasionally, until just golden, about 5 minutes. Add the wine and simmer for 1 minute. Add the 1/3 cup olive oil and the broth, and season with the salt and pepper.
Place the chicken, skin side up, in the insert and tuck the sage sprigs in between. Place the tomatoes on top and bring the mixture to a simmer. Place the insert in the slow-cooker base, cover, and cook on low until the meat nearly falls off the bone, about 3 hours.
Using a spoon, transfer the chicken, tomatoes, some of onion-garlic mixture, and braising juices to a platter. Garnish with the chopped sage and serve immediately.