Preheat oven to 425℉. Add basil, parmesan, pecorino, olive oil, pine nuts, garlic cloves, and salt to a food processor. Use the pulse setting to pulse pesto to desired consistency, scraping down the sides as needed. Set aside.
On a baking sheet, drizzle chicken with balsamic and sprinkle with salt (or marinate ahead of time if preferred). Bake chicken at 425℉ for 17-21 minutes or until the thickest part of the chicken registers at least 165 degrees. Let chicken rest for 5 minutes before using a knife and fork to pull/shred chicken into bite-sized pieces. Set aside.
Boil pasta until al dente, reserving ½ cup of pasta water when the pasta is almost done.
Add pesto, tomatoes, chicken, and red pepper flakes (optional) to drained pasta, and toss. Add a splash or all of the pasta water to moisten as needed. Toss again. Serve right away!
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Notes
Make sure to PACK your 1 ½ cups of basil. If you don’t pack the cups tightly, you won’t have enough basil!
Traditionally, Italians typically use a mortar and pestle to “grind” and mix pesto instead of a food processor (which heats up and can impact the flavor of the basil). You can use a mortar and pestle if you have one, or pulse the food processor (instead of turning it on and letting it go) to minimize the heat build-up of the blade.
You can chunk up the chicken if preferred, but I love shredded/pulled chicken for chicken pesto pasta since it soaks up the pesto even more!
It’s okay if the balsamic burns a bit on your baking sheet when baking the chicken!
It’s always best to hand-grate your cheese if time allows.
You can use just parmesan cheese (instead of both parmesan and pecorino) if preferred.
Pasta salad instead? Run the pasta under cold water after draining it, to rinse off excess starch and cool the pasta down. Toss pasta with the rest of the ingredients as the recipe is written.