In a large skillet over medium heat, melt 1 tablespoon of butter and 1 tablespoon of olive oil.
Season the chicken pieces with salt and black pepper.
Add the chicken to the skillet and cook for 5-6 minutes, stirring occasionally, until golden brown and cooked through. Remove chicken from skillet and set aside.
In the same skillet, add the minced garlic and cook for 1 minute until fragrant.
Add the orzo pasta to the skillet and toast it for 2 minutes, stirring frequently.
Pour in the chicken broth, water, lemon juice, and Dijon mustard. Stir to combine and bring to a simmer.
Cover the skillet and cook for 10-12 minutes, stirring occasionally, until the orzo is tender and most of the liquid is absorbed.
Return the cooked chicken to the skillet and stir to combine with the orzo.
Add the remaining 1 tablespoon of butter and stir until melted and incorporated.
In a small bowl, mix together the crumbled feta cheese and Greek yogurt until smooth to make the feta sauce.
Serve the chicken and orzo topped with a dollop of feta sauce and sprinkle with chopped fresh parsley.