Preheat oven to 400 degrees F. and line a baking sheet with parchment paper. Set aside.
Cut a circle around the top of each bread loaf, then, using your hand scoop out the top and gently hollow out the inside, taking care to leave a 1/2-inch wall. Reserve the torn out bread and bread top for later use. Meanwhile, toast the bread bowls in the preheated oven for 5 minutes. Remove from oven and set aside.
As the bread is toasting wilt the spinach. Heat a large skillet with a lid over medium heat. Once hot, add 1-2 tablespoons of water and the spinach, working in batches if necessary. Stir and cover. Watch for the spinach to start wilting then remove the lid, add any remaining spinach, and continue cooking until all spinach has dropped its water. Remove from heat and allow to cool.
In a large mixing bowl mix together the mayonnaise, sour cream, and cream cheese. Mix until smooth and creamy.
Add the drained and chopped artichoke hearts, lump crab meat, half of the mozzarella cheese, asiago cheese, green onion, spinach, red chili flakes, salt, pepper, and buffalo sauce. Stir well to combine.
Divide crab and artichoke mixture evenly between each bread bowl, gently packing with a spoon. Sprinkle the top of each with remaining mozzarella cheese.
Bake for approximately 10-12 minutes, or until cheese is melted and bubbly, and the dip is heated through. Serve with pita chips, baguette, or fresh veggies. Enjoy!