Bring a large pot of water to a boil and cook pasta according to package directions.
Place the peas into the colander (still frozen) and drain the pasta over the peas. The peas will thaw almost instantly. Return to the pot.
To make the pesto:
Meanwhile, add the spinach, olive oil, lemon juice, Parmesan, and seeds to a blender. Blend very well until very smooth, stopping to scrape down the sides of the bowl as needed. Season to taste with salt if needed.
Toss with the pasta and serve with additional Parmesan cheese and enjoy warm.
Notes
The pesto can be stored in the fridge for 3 days or in the freezer in a zip top storage bag (pressed flat and with as much air removed as possible) for up to 3 months.
This is enough sauce for a pound of pasta. Use a little less if your pasta package is smaller and store the leftovers for another day.
To Use this Spinach Pesto as Pizza Sauce: Simply spread the pesto onto prepared pizza crust and prepare as you normally would with regular tomato-based sauce. For a full size pizza, about 1/2 cup of pesto is usually the right amount. Adjust as needed.
Kale Pesto: Swap in baby kale or regular kale removed of the stems for the spinach. Make as directed.
Dairy-Free: Omit the cheese and consider adding an extra 1/4 cup sunflower seeds. Add a little nutritional yeast for extra flavor if desired.
Add in a handful of basil if you want, though we love this pesto without basil too.
To freeze a batch for later, add 1 cup of pesto to a freezer bag, press the air out, flatten, and seal. Freeze for up to 2 months. It will quickly defrost at room temperature. (You can also break off a chunk and add it frozen right into whatever amount of pasta you make and as you stir it in, it will thaw.)
Add a few cups of diced and cooked chicken, shrimp, or sausage if desired.
Instead of peas, you can use broccoli (toss it into the pasta water for the last 4 minutes while the pasta is cooking), diced zucchini (toss it into the pasta water for the last 2-3 minutes while the pasta is cooking), or leave out another veggie all together.