Cook the whole wheat pasta in a large pot of boiling salted water according to package instructions until al dente. Reserve 1/4 cup of pasta water and drain the rest.
While pasta cooks, season the chicken pieces with salt and pepper.
Heat 1 tablespoon of olive oil in a large skillet over medium-high heat and sear the chicken until golden brown and cooked through, approximately 6 to 8 minutes. Remove chicken from the pan and set aside.
Lower the heat to medium and add the remaining tablespoon of olive oil and minced garlic. Sauté for 1 minute until fragrant.
Pour in the chicken broth and simmer for 3 minutes, deglazing the pan by scraping up any browned bits.
Reduce heat to low. Whisk in the Greek yogurt and parmesan cheese until the sauce is smooth and the cheese has melted.
Fold in the cooked pasta, chicken, and fresh baby spinach. Toss until the spinach is wilted and the pasta is thoroughly coated.
Adjust consistency with reserved pasta water if needed. Garnish with red pepper flakes and fresh parsley.