Bring a pot of water to a boil for the pasta. Once boiling, add the pasta and continue to boil until the pasta is tender. Drain the pasta in a colander.
While the pasta is cooking, prepare the rest of the dish. Add the butter and minced garlic to a large skillet. Sauté the garlic over medium heat for about one minute, or just until it is soft and fragrant, but not browned.
Add the frozen peas and season with a pinch of salt and pepper. Sauté for a couple minutes more, or until the peas are heated through.
Add the half and half to the skillet and allow it to come up to a simmer, stirring frequently to keep a skin from forming on the surface or the bottom from scorching. Let the half and half simmer for about 3-5 minutes, or just until it reduces slightly.
At this point the pasta should be finished and drained. Add the drained pasta to the skillet and stir to combine. Sprinkle the Parmesan over the pasta and stir to combine again. Allow the heat to melt the Parmesan as you stir. Once melted, turn the heat off. Taste the pasta and add a pinch of salt and pepper, if needed.
Finally, add the drained tuna and fold it into the pasta. If you are using whole tuna chunks, break them up slightly as you stir. If you are using chunk light tuna that is already in small pieces, fold gently to avoid breaking the tuna up too much. Serve warm!