Combine chili powder, instant espresso, paprika, cumin, salt and pepper. Slowly whisk in 1-2 tablespoons to form a thick paste.
Evenly rub a thin coating of the spice mixture on each side of the chicken breast.
Place chicken breasts on a grill preheated to medium. Cook 4 to 6 minutes on each side or an internal temperature of 170°F is reached.
For the pesto, place the drained green chiles, garlic clove, lime juice, pistachios and parmesan cheese into a blender, pulse until chunky. Add ¼ cup olive oil while pulsing the blender a few more times to incorporate. Place pesto in a bowl and add salt and pepper to taste.
