Bring a pot of salted water to a boil and cook the whole wheat pasta according to package directions until al dente.
While the pasta cooks, season the chicken breast with half of the sea salt and black pepper.
Heat the olive oil in a large skillet over medium-high heat and sear the chicken until golden and cooked through, approximately 5-6 minutes per side.
Remove the chicken from the pan and let it rest for 2 minutes before slicing it into thin strips.
In the same skillet, reduce the heat to low and sauté the minced garlic for 30 seconds until fragrant.
In a small bowl, whisk together the Greek yogurt, lemon juice, lemon zest, and red pepper flakes.
Add the cooked pasta, sliced chicken, and baby spinach to the skillet, then pour in the yogurt mixture.
Gently toss everything together over low heat until the spinach is wilted and the sauce is creamy, adding a tablespoon of pasta water if the sauce is too thick.
Season with the remaining sea salt and black pepper and serve immediately.