In a large skillet over medium heat, add extra-virgin olive oil. Add the chopped shallots, and cook for about three minutes. Slice the leeks into thin discs, about a centimeter thick. Add to the pan and cook for another five minutes.
Slit the sausages lengthwise, peel off the casings, and break meat into small, equal pieces. Add to the pan and cook for eight to ten minutes. Then add the white wine and reduce for about five minutes.
Add the heavy cream and season with salt and pepper. Add the sage and thyme, mix well, and reduce for another ten minutes.
Bring a large pot of salted water to a boil. Cook the pasta until al dente. Drain, add to skillet with creamy leek sauce, and mix well. Serve immediately.