Preheat oven to 350 degrees F. In a blender combine first four ingredients (through onion powder). Cover and blend until well mixed.
In a medium bowl combine cream cheese, 1/2 cup of the Italian cheese, and the sour cream. Spread mixture in a 9-inch pie plate. Pour tomato mixture over cream cheese layer. Sprinkle with the remaining 1/2 cup Italian cheese, pepperoni, mushrooms, and sweet pepper.
Bake about 25 minutes or until bubbly and lightly browned. Serve dip with bread wedges.