Cut the top off the tomatoes and remove the pulp, leaving only the walls, about 1 cm thick. Cut the pulp into small pieces. Sprinkle the inside of the hollow tomatoes with salt and turn over onto paper towels to allow the liquid to drip onto them.
In a small skillet over medium heat, heat 2 tablespoons of butter, pour onions into a preheated skillet, and fry, stirring occasionally, until soft. Place the tomato pulp in a skillet and cook, stirring occasionally, until most of the liquid has evaporated. Remove the pan from the stove, add rice, cheese, parsley, basil and garlic salt to the tomato mixture. Turn on the oven to preheat to 180 degrees.
Fill the hollow tomatoes with this mixture and sprinkle with the remaining butter on top. Place the stuffed tomatoes in a deep oiled baking sheet and immediately place in the preheated oven. Bake the stuffed tomatoes for about 15-20 minutes.