1 stalkcelery, diced, plus a handful of celery leaves
1 smallclove garlic, minced
2 cupsbread cubes (from about 1/2 baguette)
1 cupChopped Basil
1/2 cupWalnut pieces
1/3 cupParmesan cheese
Preheat oven to 400°F.
Using a serrated knife, slice off top quarter of each tomato and reserve tops. Scoop out pulp from inside each tomato and transfer to a food processor. Add 2 tablespoons olive oil and cayenne to food processor and process until smooth; pour into 9×13 inch baking dish.
Heat remaining 2 tablespoons olive oil in large skillet over medium-high heat. Add sausage, herbes de Provence, bell pepper, onion, diced celery and garlic. Cook, stirring, until sausage browns, about 5 minutes.
Transfer sausage mixture and bread cubes to food processor and pulse until chopped. Pack tomatoes with sausage-bread mixture so stuffing is domed on top. Put stuffed tomatoes in baking dish on top of sauce.
Place basil, walnuts, cheese and celery leaves in food processor and chop. Sprinkle onto tomatoes. Put tomato tops, cut-side down, between stuffed tomatoes. Bake until stuffing is golden, about 20 minutes. Cover each tomato with a top and serve with sauce.