Cook the pasta according to package instructions until al dente, then drain, reserving a cup of pasta water.
In the same pot, heat a drizzle of olive oil over medium heat and sauté the diced onion until translucent, about 3-4 minutes.
Add minced garlic to the pot and sauté for another minute until fragrant.
Stir in the heavy cream, bringing it to a gentle simmer and allowing it to thicken slightly.
Add the tuna, frozen peas, and half of the Parmesan cheese, stirring to combine.
Fold in the cooked pasta, mixing thoroughly, adding reserved pasta water as needed to achieve desired sauce consistency.
Season with salt and pepper, adjusting flavors, and mix in the remainder of the Parmesan cheese before serving.
Serve garnished with fresh parsley for a vibrant touch.
