Preheat your oven to 350°F. In a large Dutch oven or baking dish, melt butter over medium heat and sauté the diced onion until softened, about three minutes. Add minced garlic and cook for another minute until fragrant and the aromatics are fully released.

Season the chicken pieces with salt, pepper, and dried thyme on both sides. Working in batches if needed, brown the chicken in the same pot for three to four minutes per side until golden but not cooked through. The browning step adds incredible depth to this summer chicken rice casserole crowd recipe.

Remove the chicken and set aside temporarily. In the same pot, combine the long grain white rice with the cream of mushroom soup, stirring well to coat every grain evenly. Pour in the chicken broth slowly while stirring to prevent lumps from forming in the sauce.

Return the chicken pieces to the pot and stir in the frozen mixed vegetables, making sure everything is distributed evenly. Bring the mixture to a simmer on the stovetop for two minutes, then cover the pot with a lid or aluminum foil to trap steam.

Transfer the covered pot to the preheated 350°F oven and bake for forty to forty-five minutes until the chicken is cooked through completely and rice has absorbed the liquid. The internal temperature should reach 165°F when checked with a meat thermometer in the thickest piece.

Remove from the oven and sprinkle the grated cheddar cheese and breadcrumbs evenly over the top. Return to the oven uncovered for three to four minutes just until the cheese melts and breadcrumbs turn golden brown.

Let it rest for five minutes before serving, then garnish with fresh chopped parsley for color and brightness that elevates the presentation beautifully.