Preheat the grill to medium. In a bowl combine the lime juice, two teaspoons of ginger, garlic, and pepper flakes. Add the Jumbo Shrimp and pineapple chunks. Toss to combine and let the mixture marinate while the grill heats up for 15 minutes. Remove the shrimp and pineapple from the mixture. Soak wooden skewers in water for at least 15 minutes. Wrap the shrimp with the prosciutto ham. Place the shrimp and pineapples on skewers, alternating between the two. Place the kebobs on the grill and cook for 3 to 4 minutes per side. Remove the skewers from the grill. Heat a saucepan over medium heat. Add the rum, the remaining ginger, garlic, and shallots. Bring the mixture to a boil. Reduce the heat to a simmer and allow the mixture to reduce by one half. Add the butter to the sauce, one teaspoon at a time, whisking well until all of the butter has been mixed in. Place the shrimp on a platter and drizzle with the butter sauce. Garnish with chopped cilantro.