Season the chicken breasts evenly with salt and black pepper on both sides.
Heat the olive oil in a large skillet over medium-high heat.
Add the chicken breasts to the skillet and cook for 5-6 minutes on each side, or until golden brown and cooked through. Remove chicken from the skillet and set aside.
Reduce heat to medium and add the minced garlic to the skillet. Sauté for 1 minute until fragrant, stirring constantly to avoid burning.
Pour in the chicken broth, scraping the bottom of the skillet to loosen any browned bits.
Stir in the heavy cream, lemon juice, orange juice, lemon zest, orange zest, fresh rosemary, and Dijon mustard.
Simmer the sauce for 5-7 minutes, stirring occasionally, until it thickens slightly.
Return the cooked chicken breasts to the skillet and spoon the creamy citrus sauce over them.
Cook for an additional 2-3 minutes to warm the chicken through and allow flavors to meld.
Serve the creamy citrus chicken hot, garnished with extra rosemary if desired.