Ultimate Spinach Artichoke Delight

Preheat the oven to 350 degrees F (175 degrees C).
Place garlic cloves in a small oven-safe dish and roast in the preheated oven until softened and fragrant, about 20 minutes.
Set roasted garlic cloves aside to cool.
In a large mixing bowl, combine the thawed and drained spinach with the chopped artichoke hearts.
In a skillet over medium heat, melt butter.
Cook and stir mushrooms until softened, about 10 minutes.
Mix in the green onions and cook until soft, about 5 more minutes.
Transfer the mushroom mixture to the bowl with the spinach mixture.
Remove cream cheese from wrapping, place it in a microwave-safe bowl, and warm in the microwave until very soft, about 1 1/2 minutes.
Stir the softened cream cheese into the spinach mixture, then add sour cream, water chestnuts, Parmesan cheese, mayonnaise, garlic salt, and lemon juice.
Squeeze the roasted garlic out of the skins, mix thoroughly into the spinach mixture.
Spoon the delightful mixture into a round 2-quart baking dish.
Bake in the preheated oven until the casserole is hot and bubbly, about 30 minutes.
Spread French-fried onion rings over the top, return to the oven, and bake until the onion rings are lightly browned, an additional 5 to 10 minutes.