In a large saucepan, heat butter. Add garlic and cook for ~1 minute. . Whisk in flour until lightly browned, about 1 minute. Gradually whisk in chicken broth and cook, whisking constantly, until incorporated, about 1-2 minutes.
Whisk in flour and cook for ~1 more minute. Add in chicken broth, stirring constantly until combined.
Stir in heavy cream, sun dried tomatoes, Parmesan, Italian seasoning, and salt/pepper to taste. Heat stirring constantly for ~2 minutes.
Combine pasta, sausage, and sauce. Garnish with parsley if desired.