Prepare the pasta dough by combining the semolina and salt in a large mixing bowl. Form a small well in the center of the mixture. In a bowl, beat the eggs and olive oil together until combined. Pour into the well in the semolina. Slowly mix the semolina into the egg mixture, mixing until it is combined. Cover the bowl with plastic wrap and let rest for 30-40 minutes. Meanwhile, prepare the filling by heating the butter in a skillet over medium heat. Add the bell pepper, onion, eggplant, and mushrooms. Cook, stirring frequently, until the vegetables are tender. Add the garlic, parsley, and basil and cook for 1 more minute. Season to taste with salt and pepper. Remove the pan from the heat and set aside to cool to room temperature. Bring a large pot of water to a low boil over medium-high heat. Turn the dough out onto a lightly floured work surface and roll out into thin sheets, or alternately use a pasta machine. Cut the dough into 4-inch squares. One at a time, brush a pasta square with beaten egg. Mound some of the filling onto the square and cover with another pasta square. Press the dough lightly to press out any excess air and then seal the edges. Repeat with remaining dough and filling. Drop the ravioli into the boiling water and cook for 4 minutes or until al dente. Remove the pasta from the water with a slotted spoon and place on individual serving plates. While the pasta is cooking, prepare the butter sauce by heating the butter, herbs, garlic, salt, and pepper in a small saucepan over medium heat. Pour the sauce over the ravioli. Garnish each serving with some grated Parmesan. Serve immediately.