Bring a large pot of salted water to a boil.
In a large skillet over medium-high heat, add crumbled sausage (if your sausage is in casings, remove) and cook until browned.
If needed, you can add a little olive oil to the skillet (but you may have enough from the sausage). Add garlic to skillet and cook 1 minute, until fragrant. Stir in anchovy paste, red hot pepper flakes, and sun-dried tomatoes and cook for another 3 minutes.
Add in crushed tomatoes, stir, and let simmer for 5 minutes.
Stir in olives and capers and let mixture continue to simmer for another 10 minutes.
While sauce is simmering, add spaghetti to boiling water and cook until al dente. Drain.
Add spaghetti to skillet and toss everything together to coat pasta in sauce.
Serve pasta with grated parmesan and chopped parsley.