Bring a pot of water to a boil and add the pasta. Set the timer according to package directions (generally 8 – 12 minutes).
Add the olive oil and chopped garlic to a pan and turn to medium heat. Let simmer just until the garlic begins to sizzle, then add the tomatoes and tuna and turn to medium-low heat. Season with salt and pepper.
When the pasta is cooked scoop it out of the pot using a slotted spoon and add it directly to the pan. Add the spinach and toss until the hot water from the pasta has wilted the spinach.