Boil the pasta: Bring a large pot of salted water to a boil. Cook the pasta until just al dente. Reserve 1 cup of pasta water, then drain.

Prep your aromatics: While the pasta cooks, mince the garlic and zest half a lemon. Halve the cherry tomatoes if using.

Build the base: In a large skillet, warm 1 tablespoon olive oil over medium heat. Add garlic and cook 30–45 seconds until fragrant. Don’t brown it.

Add tuna: Flake in the drained tuna. Stir gently to warm it through. If it looks dry, add another drizzle of oil.

Creamy sauce time: Pour in the cream and bring to a gentle simmer. Add 1/4 cup pasta water and the lemon zest. Stir in the pesto (start with 1/3 cup). Simmer 1–2 minutes until slightly thickened.

Season: Add a pinch of salt, a few grinds of black pepper, and red pepper flakes if you like heat. Stir in the Parmesan until melted and smooth.

Toss with pasta: Add the drained pasta to the skillet. Toss to coat, adding more pasta water as needed for a glossy, silky sauce that clings to the noodles.

Finish and brighten: Stir in a squeeze of lemon juice to taste. If using spinach, fold it in now until just wilted. Add cherry tomatoes for a fresh pop.

Adjust and serve: Taste and adjust salt, pepper, and pesto. Top with extra Parmesan and a drizzle of olive oil. Serve hot.