In a large bowl, combine the cream cheese, cheddar cheese, onions, mayonnaise, sour cream, and Worcestershire sauce. Add salt and pepper to taste.
Cut the center out of one of the loaves of bread. Slice the section of bread that is removed into cubes and reserve those for later.
Spoon the cheese mixture into the cavity you created in the bread. Place the cheese-filled bread on a baking sheet. Bake for 35-40 minutes or until the cheese is bubbling and starting to darken on top.
In the meantime, slice the second loaf of bread into cubes for serving. You can also serve the dip with sliced cucumbers for a bread-free option.
Notes
Special note: Audrey made this a little spicer by raiding my spice cabinet and adding something she found there. Sorry - I don't know what it was.