Preparation / Directions:
Let the spinach thaw out.
Put all the cheeses and spinach (and artichoke if you're adding it) in a mircowavable bowl and stir to mix. Heat in microwave on medium to medium-high heat until cheese is all melted, about 6-8 minutes. Stir about halfway through cooking. After all heated and cheese is all melted, stir to mix everything together. sprinkle diced tomatoe (and any other toppings you like) on the top.
This dip is also great in a low fat variety, using part-skim cheddar cheese and fat free cream cheese.
Also nice in a break bowl (do not microwave in the bread)