Cook the pasta 2 minutes less than the package directions—reserve 2 tablespoons of the pasta water.
Heat the olive oil in a small saucepan over medium heat and add the garlic. Cook, stirring, just until fragrant, and remove from the heat. Add the tuna and tomato sauce.
Bring to a simmer and season to taste with salt and add the red pepper flakes. Stir in olives.
Add the spinach, reserved pasta water and the cooked pasta. Stir until the spinach is wilted.
Serve and enjoy!