Preheat your oven to 375˚F. This ensures that your dish will cook evenly and perfectly, creating a golden brown topping.
Lay the chicken breasts flat in a large baking dish. Season with garlic powder, 1/4 tsp salt, and 1/4 tsp pepper. Make sure to coat them well; this adds flavor directly to the meat.
In a separate bowl, mix the cheeses together, then set aside about a cup of this mixture. This will be your topping, and it’s what makes this dish irresistible!
In another large bowl, combine the mayonnaise, sour cream, Dijon mustard, finely chopped onion, remaining salt, and pepper. Whisk until well combined; this creamy mixture is the heart of your bake.
Add the remainder of the cheese mixture to the creamy mixture and fold in the chopped spinach and diced artichoke hearts. Stir gently to combine, being careful not to break the artichoke pieces.
Spread the creamy mixture evenly over the chicken in the baking dish. Make sure each piece is well covered; this will keep the chicken moist while it bakes.
Top with the cup of cheese you set aside earlier. This cheesy layer will create a beautiful crust as it bakes.
Place the baking dish on the middle rack of your oven and bake for 30 to 40 minutes. The chicken should be cooked through, reaching an internal temperature of 165˚F.
Once baked, remove the dish from the oven and let it rest for a few minutes. This helps the flavors set and makes serving easier.
Serve hot and ENJOY! This dish is best enjoyed fresh out of the oven, allowing everyone to dig in while it’s warm and bubbly.
