Add one chopped onion and cook until the onion is slightly translucent. Approximately 2-3 minutes.
Add the pasta and gently push it under the liquid until it's submerged.
*Note - If more liquid is needed, add more water so the pasta is submerged but not overly so.
Partially cover the pot (leaving the spoon in the pot to prevent a boil-over), reduce the heat to medium/low, and simmer for approximately 5 - 6 minutes.
Cook for an additional 1 - 3 minutes, uncovered until the pasta is al Dante.
To finish, add the drained capers and stir.
Serve hot, and top with Parmesan cheese, if desired.