Boil a pot of salted water and cook the pasta al dente according to the package instructions. Drain the pasta and return back to the pot to keep warm.
Heat olive oil and butter in a skillet over medium heat. Add the garlic and cook until fragrant, about 30 seconds. Stir in the tuna (breaking up into pieces), lemon zest, lemon juice, salt and pepper and toss to combine.
Remove from heat and add the cooked pasta to the skillet. Toss until the pasta is evenly coated.
Top with olive tapenade. Sprinkle with parmesan, fresh parsley or red pepper flakes if desired.