Preheat the oven to 375°F.
In a large bowl, combine the shrimp, bread crumbs, cream cheese, mayonnaise, green onions, red bell pepper, garlic, Old Bay seasoning, lemon juice, salt, and black pepper. Mix until well combined.
Slice the French bread in half lengthwise and scoop out some of the soft bread from the center to create a hollow space for the filling.
Spoon the shrimp mixture evenly onto each half of the bread. If desired, sprinkle shredded cheddar cheese on top.
Place the stuffed bread on a baking sheet and bake for 20-25 minutes, or until the shrimp are cooked through and the bread is golden brown.
Remove from the oven and let cool for a few minutes before slicing. Garnish with fresh parsley if desired.