The spinach can be pulled from the freezer and thawed on a plate in the refrigerator for about ten hours. Alternatively, the spinach can be thawed gently in the microwave. Once thawed, place the spinach in a strainer and press out the excess water.

Heat the olive oil in a ten-inch non-stick skillet over medium heat and add the minced garlic. Cook very slowly and stir frequently. Do not allow the garlic to brown or it will become bitter.

Add the spinach and then the flour slowly and cook for about one minute. Stir continuously to blend the spinach and flour. Cook gently so the mixture doesn't brown.

Slowly add the cold milk, whisking to keep from forming clumps. Blend in all of the milk until the sauce is smooth and begins to thicken.

When the sauce is smooth, add the Parmigiano-Reggiano and whisk as it melts until the sauce is creamy. Reduce the heat to very low.

In a large pot heat the water to a boil. Add the fettuccine and cook until just tender (about 12 - 15 minutes for dried pasta). Drain well and then add the pasta to the sauce, tossing to coat thoroughly. Sprinkle the minced parsley over the top and serve.