Zest 1 whole lemon. Then squeeze the juice from both lemons into a small bowl. Combine pecorino romano, lemon zest, and lemon juice. Add 3 tablespoon olive oil. Set aside.
In a pot bring water to a boil. Salt the water and add the spaghetti. Boil until al dente. Save 1 cup of pasta water.
Bring a saucepan to medium heat. add 2 tablespoon of olive oil. Add the crushed garlic and saute until browned on both sides. Remove the garlic. Add the spinach and wilt for 1 minute. Push the spinach to the side of the pan and add butter. Once melted add your spaghetti and mix it with the spinach. Remove from the heat and add the lemon mixture with ½ a cup of pasta water. Stir until the pasta becomes creamy. Add more pasta water to adjust the texture.