In a medium pot, bring 1/2 cup water to boil along with optional thyme sprigs, wine and lemon slices. Once water has started to boil add lobster tails. Cover and steam for 4 minutes. Remove cover and add shrimp. Cover and steam for additional 4 minutes. If choosing to use lobster tails, skip that step and just steam the shrimp for the 4 minutes.
Chop lobster and shrimp into small chunks.
In a medium bowl, add seafood, parsley, cajun seasoning, garlic powder, onion powder and lemon juice. Mix thoroughly. Taste mixture and add more cajun seasoning if needed.
Heat 2 tbsp of butter and 2 tsp of oil in a skillet over medium-low heat. Butter two slices of bread on one side, and place opposite side down in skillet. On one slice of bread, add a layer of sharp and white cheddar, a generous amount of the seafood mixture and another layer of cheese. Top with other slice of bread and grill on each side until golden brown and cheese is melted. I typically flip approximately 4-5 times to get it golden brown to my liking.
Repeat steps until as many sandwiches as possible are made.