In blender, combine onion, garlic, and crushed tomato. Blend until smooth.
Add proto-soup to large dutch oven over medium heat along with butter, stock, sugar, vinegar, salt, pepper flakes, and dried herbs. Bring to simmer and keep it there for 20 minutes.
As soup simmers, cube bread and place on cookie sheet along with the pepperoni. Toast under the broiler for 3-4 minutes or until bread is browned and pepperoni is just crisp.*
Once soup has simmered and toppings done, make a bowl of soup! Top with the cheese, croutons, pepperoni, pepperoncini, and a grind of pepper. Enjoy. Don't burn your mouth.
Notes
*Yep. Broiling the pepperoni. It's genius. I know.