Pre-heat the oven to 350 degrees. In a medium bowl, combine cream cheese, chopped onion, mayonnaise, crab meat, garlic powder, salt, and pepper. Mix well. Spread the mixture into a 1-quart baking dish. Place into the oven and bake for 20 minutes.
Meanwhile, cut a circle in the top of the bread and scoop out the inside to create a bread bowl. Tear the removed bread into pieces for dipping.
After 20 minutes, remove the crab dip from the oven and stir well. Spoon the mixture into the hollowed out loaf. Place the bread bowl and the pieces of torn up bread onto a baking sheet. Place into the oven and bake for an additional 10 minutes. Serve hot.