This is likely going over some pasta with shrimp and scallops but I can think of half a dozen other uses as well. Just alone over pasta would be enough, come to think about it.
When I make pesto I use cashews instead of pine nuts. The reason is simple: it's different. I also find that cashews tend to impart a more buttery texture to the pesto which gives it a nice mouthfeel.
Also, before embarking on adding peppers to this you need to judge the heat of them first. The heat here will build on you the more you eat of the sauce. In addition, the next day the flavors will have mellowed out with each other and result in a better tasting - and likely hotter - sauce. As there is a lot of fat in this (it is pesto, after all), said fat will line your mouth and deceive the presence of most of the heat...until it washes off your tongue and the capsaicin is left sticking to it as you eat more.
Resist the urge to add more garlic: the highlight of this pesto are the chilies. I know I know, I too am part of the more-garlic-is-better crowd but this is one area where less is, in fact, more.
10 oz baby spinach leaves
1 packed cup of fresh basil
2 - 4 roasted Hatch or Anaheim chili peppers
2 cloves garlic
1/3 cup unsalted, roasted cashews
4 TBS grated Parmesan
~1 cup extra virgin olive oil
~1 cup of boiling water
Quick blanch the baby spinach by setting it in a large colander over the sink and pouring 2 quarts of boiling water over the leaves. Immediately run cold water over the spinach to cool. Squeeze out as much water as you can and then lay the leaves on a kitchen towel and roll the towel to dry the leaves. Give the towel a gentle twist to aid this.
Remove the skin and seeds from the chili peppers and dice into dime sized chunks.
In a food processor add the cashews and pulse a few times until they're chopped up. Add the basil, spinach, chili peppers, and peeled garlic cloves to the processor and run for about 30 seconds, stopping to push the mixture down the side. Do this about two times. Add the cheese, ¼ TSP of salt and pulse to mix.
With the processor running add the olive oil in a steady stream. You're nearly done adding oil when the pesto is no longer sticking to the sides of the processor and has become a smooth sauce with the consistency of...pesto. When this happens add another ¼ cup of oil. Finally, add about 2 - 3 TBS of boiling water to help incorporate and smooth out.