Slice the top of the bread boule off and remove the insides.
Spread ½ cup of the marinara on the bottom of the boule, then layer with half of the mozzarella, 5 ounces of the pepperoni, onions, basil, sausage, peppers, the other ½ cup of marinara, the remaining mozzarella, and half of the white cheddar, and place the cap of the bread boule on top.
Wrap the bread bowl in foil, then press with a heavy object for 30 minutes.
Remove the foil and sprinkle the remaining cheddar and pepperoni on top. Bake for 30 minutes, until cheese is golden brown.