Slice the top off the tomato (reserve), then scoop out the pulp inside. Sprinkle with salt and let sit upside to drain any excess moisture.
In a hot skillet with oil, fry the sausage, seasoning, green pepper, onion, celery and garlic until the sausage is fully cooked.
Transfer sausage mixture to a food processor, add bread cubes and pulse until evenly chopped. Stuff into the tomatoes,and place in a greased oven proof dish (put tomato tops in dish beside tomatoes).
In the food processor, combine the basil, walnuts and cheese and pulse until smooth. Sprinkle on top of the sausage, then bake at 400°F for 20 minutes.
Remove from oven and put the tops gently back on top of the stuffed tomatoes.