Preheat oven to 350°F.
In a medium sauté pan over medium to high heat, add pepperoni and cook until crispy. Remove and drain on paper towels. When cool, crumble pepperoni and set aside 3/4 for tossing in stuffing, reserving 1/4 for garnish.
To the remaining grease in the pan, add yellow onions, peppers, celery, garlic and sun-dried tomatoes, and sauté until onions are translucent. Remove and let cool.
In a small bowl, whisk together the eggs, pepper and paprika. Place foccacia cubes, parsley and green onions in a large mixing bowl and pour egg mixture over everything. Add sautéed vegetables and crumbled pepperoni, and mix all ingredients thoroughly. Slowly add chicken stock, tossing everything so it's absorbed evenly.