Pasta: Bring a pot of salted water to a boil. Cook the pasta according to package directions.
Garlic: Mince or grate the garlic. Heat a large pan with olive oil. Add in the garlic and sauté over medium-high heat while stirring continuously for 1 minute.
Spinach: Add the baby spinach to the pan and stir over medium heat until wilted. If using frozen spinach, stir until melted. Note that you may need to add less pasta water since the spinach already releases some as it melts.
Make the sauce: In the pan, combine the hummus, pasta water, lemon zest, and lemon juice. Then, season with pepper.
Toss: Drain the cooked pasta and add it to the pan. If the sauce is too thick, add a splash of warm water. Serve immediately.
Notes
Use pasta water to thin out the sauce. The starchy, salted water helps bind everything together and seasons the sauce at the same time. But if you accidentally drained the pasta before saving some of the water, you can use regular warm water instead.
Don't worry if the sauce looks a little runny at first. It will have the perfect consistency once you toss it with the pasta.