Begin by placing the boneless, skinless chicken breasts at the bottom of your slow cooker. Season them generously with salt, pepper, dried rosemary, and thyme, ensuring they are well-coated.
In a medium mixing bowl, combine the diced onion, minced garlic, lemon zest, and freshly squeezed lemon juice. Stir this mixture well and then spread it evenly over the seasoned chicken.
Carefully pour the chicken broth into the slow cooker, taking care not to disturb the chicken or the seasoning. Next, sprinkle the dry long-grain rice evenly over the top without stirring, allowing it to sit on the broth.
Secure the lid on the slow cooker and set it to cook on low for 4 to 5 hours or on high for 2 to 3 hours. The chicken should be tender and thoroughly cooked, while the rice will have absorbed most of the liquid by the end of the cooking time.
Approximately 30 minutes before you plan to serve, stir in the frozen peas. Replace the cover to allow the peas to heat through and become tender.
Once the cooking time is complete, shred the chicken directly in the slow cooker using two forks, mixing it gently with the rice. Use a fork to fluff up the rice for an inviting texture.
Before serving, taste your creation and adjust the seasoning if needed, adding extra salt, pepper, or a splash more lemon juice for brightness.
Notes
Serve with fresh parsley and lemon slices for garnish.