Bring a pot of salted water to a boil and cook the whole wheat penne according to package directions until al dente.
While the pasta cooks, season the chicken breast with sea salt and black pepper on both sides.
Heat the olive oil in a large skillet over medium-high heat and sear the chicken until golden and cooked through, about 5-6 minutes per side.
Remove the chicken from the skillet, let it rest for a few minutes, then slice it into bite-sized strips.
In the same skillet, lower the heat to medium and add the minced garlic and chopped sun-dried tomatoes, sautéing for 1 minute until fragrant.
Add the fresh baby spinach to the skillet and toss until just wilted.
Drain the pasta, reserving a small splash of pasta water, and add the pasta to the skillet along with the sliced chicken and basil pesto.
Toss everything together until well-coated, adding a tablespoon of pasta water if needed to loosen the sauce, and serve immediately.