Rip bread into approximately 1-inch bite-sized pieces and put into baking dish.
Mix tomato paste with boiling water, brown sugar, salt and melted butter together over low heat. Once it is completely melted, while constantly stirring, bring to a rolling boil until you see bubbles appearing.
Pour bubbling mixture over bread, coating thoroughly. You want the tomato mixture to get to the bottom of the baking dish. If needed, gently mix together bread and tomato mixture. If you feel you need a bit more bread, add it in.
Bake in 350 degrees over for 30 minutes until lightly brown on top.