Bring a small pot of salted water to a boil and cook the brown rice penne according to package directions until al dente.
While the pasta cooks, season the chicken breast with sea salt, black pepper, and dried oregano.
Heat the olive oil in a 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 and set aside to rest, then slice into thin strips.
In the same skillet, lower the heat to medium and add the minced garlic, sautéing for 1 minute until fragrant.
Pour in the chicken broth to deglaze the pan, scraping up any browned bits from the chicken.
Stir in the Greek yogurt and parmesan cheese, whisking constantly until the sauce is smooth and slightly thickened.
Add the baby spinach to the skillet and stir until just wilted.
Toss the cooked pasta and sliced chicken into the sauce, coating everything evenly before serving.