Cook bacon in large skillet over medium heat 4 to 5 minutes or until partially cooked, stirring occasionally.
Drain grease and return bacon to skillet.
Sprinkle chili powder over shrimp and add shrimp and pineapple to skillet. Cook 3 to 5 minutes or until shrimp and bacon are cooked. Stir occasionally.
Toast muffins, Place on baking sheet and cover each muffin half with cheese.
Broil 2 minutes or until cheese is melted. Top with bacon/shrimp/pineapple mixture. Sprinkle with cilantro or parsley.