Step 1

Place oven rack to the center position. Preheat oven to 450°F.

Step 2

Drizzle both sides of the chicken breast with olive oil. Season both sides of the chicken with salt and pepper.

Step 3

Place chicken in an ovenproof baking dish or skillet.

Step 4

Bake in preheated oven until the internal temperature of the chicken is no longer pink and reaches an internal temperature of 165°F, about 15 to 18 minutes.

Step 5

Meanwhile, make the pesto. Place the basil and spinach in a resealable plastic bag. Use a rolling pin to lightly bruise the herbs and greens. Transfer to a food processor or blender.

Step 6

Heat a medium-sized skillet over medium heat. Toast garlic until the outsides are lightly browned, shaking pan occasionally, about 8 minutes. Peel garlic and add to food processor.

Step 7

Place walnuts in the same pan and toast over medium heat, 3 to 4 minutes. Transfer to food processor.

Step 8

Add 1/2 teaspoon salt to the food processor.

Step 9

Process pesto by pulsing five times to help break down the greens.

Step 10

Turn food processor on low speed, as it's running slowly drizzle in 1/2 cup olive oil until a smooth pesto with some smaller pieces is formed, about 10 seconds from start to finish.

Step 11

Add the parmesan cheese to the pesto and process on low speed for 5 seconds.

Step 12

Taste and season with salt and pepper as desired. Transfer pesto to a small bowl.

Step 13

Brush some pesto sauce on each cooked chicken breast. Transfer to a serving platter.

Step 14

Top chicken with chopped walnuts, tomatoes, and cheese. Serve extra pesto sauce on the side.