Bring a large pot of salted water to a boil over high heat. Add the pasta and cook until al dente according to package directions. Reserve 1 cup of pasta cooking water, then drain the pasta and return to the pot to stay warm.,

In a large skillet, heat the olive oil over medium heat. Add the onions and cook for 5-7 minutes or until fragrant and they soften. Add the garlic, and cook for 30 seconds, or until fragrant. Add the spinach and cook for 1 minute, or until is slightly wilts.,

Add the hummus, about ½ cup of the pasta cooking water, the lemon juice and lemon zest, and stir until a creamy sauce forms. Add more pasta water to thin the sauce a little at time, as desired.,

Transfer the cooked pasta to the skillet, turn off the heat and toss everything together. Top with basil and crushed red pepper.,

Serve immediately with parmesan cheese or basil, if desired.