Step 1

Thaw the spinach at room temperature or in the microwave. Squeeze out the excess water. Set the spinach aside. Bring a large pot of water to a boil, then add the macaroni noodles. Boil for 7-10 minutes, or until al dente. Drain the macaroni in a colander.

Step 2

While the pasta is boiling, prepare the sauce. Add the butter and flour to a small sauce pot. Heat and stir the butter and flour over medium heat until it forms a creamy paste and begins to bubble. Continue to stir and cook for about one minute more.

Step 3

Whisk the milk into the butter and flour, then allow it to come up to a simmer, while whisking. When it reaches a simmer, the sauce will thicken. Remove the sauce from the heat.

Step 4

Whisk the Romano (or Parmesan) and pesto into the sauce until smooth. This will further thicken the sauce. Season the sauce with salt and freshly cracked pepper. Make sure the sauce is well seasoned as the flavors will be less concentrated once the pasta and spinach are stirred in.

Step 5

Return the cooked and drained pasta to the large pot (heat turned off) and add the thawed spinach. Pour the sauce over top, then stir until everything is combined and coated in sauce. Serve immediately.