In a bowl, mix together the butter, lime juice, garlic, and spices, until well-combined. Add the shrimp and stir to evenly coat. Let marinade for 10-15 minutes.
Meanwhile, heat the grill or grill-pan over medium-high heat. Add the pineapple slices to the grill and cook until golden, about 3-4 minutes per side. Remove from the grill and set aside. Add the shrimp to the grill pan and cook until opaque, about 2-3 minutes per side, depending on size.
Cut the grilled pineapple rings into chunks. Divide the shrimp and pineapple evenly among the tortillas, top with the jalapeño, cabbage, cheese and cilantro.
Serve immediately and enjoy!