Bring a medium pot of salted water to a boil and cook the whole wheat penne until al dente, about 8-10 minutes.
While the pasta cooks, pat the chicken breast dry with a paper towel and season both sides with sea salt and black pepper.
Heat the olive oil in a large skillet over medium-high heat. Add the chicken and sear until golden brown and cooked through, about 5-6 minutes per side.
Remove the chicken from the skillet, let it rest for 2 minutes, then slice into thin strips.
In the same skillet, reduce heat to medium and add the minced garlic and sundried tomatoes, sautéing for 1 minute until fragrant.
Add the fresh baby spinach to the skillet and toss until just wilted.
Drain the pasta, reserving 2 tablespoons of pasta water.
Add the cooked pasta, sliced chicken, and basil pesto to the skillet, tossing everything together with the reserved pasta water to create a light sauce.