Put 1 teaspoon of dried lemon peel in a bowl, or zest a lemon to get about the same equivalent from one of your lemons.
Cut open the lemons and squeeze the juice out of the lemons. After squeezing the lemons, scrape out some of the flesh from the lemons and put them in a bowl. This will give a more lemon flavor to your dish.
Combine your your lemon mixture with the mascarpone cheese, pepper, salt, and nutmeg. Mix thoroughly in a bowl.
Place the cheese mixture in the pot with your pasta on low heat.
Place the spinach in the pot with the pasta and sauce, and cook until the spinach looks wilted. Stir constantly for about five minutes to keep from burning. Note: I put the spinach in whole. If you want smaller pieces, cut it up prior to this step. This may also speed up the cooking process.