Preheat oven to 400 degrees F. Brush inside and out of the avocados with the lemonjuice to prevent discoloration. Place on a parchment lined baking sheet. Set aside.
In a medium bowl add the cubed bread, tomato, spinach, bacon, mayonnaise, koshersalt, and blackpepper. Toss lightly to combine. Fill each avocado half with ¼ of the bread mixture, packing lightly.
Bake for 10-13 minutes, or until the bread stuffing begins to brown. Remove and serve immediately.