Bring a small pot of salted water to a boil and cook the whole grain pasta according to package directions until al dente.
While the pasta cooks, heat the olive oil in a large skillet over medium-high heat.
Add the cubed chicken breast to the skillet and sauté until golden brown and cooked through, about 6-8 minutes.
Stir in the minced garlic and sliced zucchini, cooking for 3 minutes until the zucchini is tender-crisp.
Reduce the heat to low and add the baby spinach, stirring until just wilted.
In a small bowl, whisk together the Greek yogurt, lemon juice, lemon zest, sea salt, and black pepper.
Drain the pasta, reserving two tablespoons of pasta water, then add the pasta and the yogurt mixture to the skillet.
Toss everything together gently over low heat until the sauce is creamy, adding reserved pasta water if needed, and garnish with fresh parsley.