Step 1

In large container, dissolve 1/4 cup salt and 2 tablespoons sugar in 2 cups warm water. Place chicken in brine and chill for one hour.

Step 2

While chicken is brining, place parsley, pine nuts, garlic, olive oil, and chili flakes in food processor. Pulse until smooth. Transfer to bowl and stir in Parmesan. Season to taste with salt and pepper.

Step 3

Remove chicken from brine and pat dry with paper towels. Halve chicken pieces on the bias so that the pieces are of approximately equal 1/4- to 1/2-inch thickness. Heat grill pan over medium heat. Lightly brush surface with oil and cook chicken until just cooked through (an instant-read thermometer inserted into center of chicken should read 150 to 155°F), 3 to 5 minutes per side. Transfer to cutting board and let rest 5 minutes. Slice into 1/4-inch slices.

Step 4

Bring 4 quarts of salted water to boil in large pot over high heat. Add pasta and cook to al dente. Drain and return to pot, reserving 1 cup cooking liquid. Stir in pesto and baby spinach until wilted. Season to taste and stir in chicken. Stir in extra pasta water to thin sauce to desired consistency. Serve with extra grated Parmesan on the side.