Preheat the grill or broiler.
In a hot pan heat the olive oil. Place shrimp into pan (do not turn shrimp). Season with salt and pepper and add garlic. Deglaze with limoncello. Add a squeeze of lemon and the zest of half a lemon. After 3 minutes, turn shrimp over, turn the heat off and add chili flakes, more lemon juice and chopped parsley. Drizzle with olive oil.
Meanwhile, grill or toast the bread until golden brown. Place 1 slice of bread on each plate. Divide the shrimp over the bread. Divide and spoon the sauce over the shrimp. Sprinkle the bruschetta with remaining lemon zest and serve immediately.