In a medium-sized skillet over medium-high heat, melt butter. Pour about 3 Tbsp of the butter into a small bowl and set aside, keeping warm.
Add panko and minced garlic to the remaining 2 Tbsp butter in the skillet and cook until panko is golden, about 3-4 minutes, being sure to stir often.
Stir in the thyme and about ⅛ teaspoon salt. Remove from the heat.
Heat grill for direct cooking over high heat, about 450° to 550°F.
In a medium-sized bowl combine the scallops, Cajun seasoning, ½ tsp salt, and ¼ tsp pepper. Toss scallops in the seasonings and add 2 Tbsp melted butter and toss to coat.
Place scallops on the grill, flattest side down. Grill over direct high heat, with the lid closed. After two minutes, turn scallops with tongs. If scallops are resistant to turning, continue to grill another few seconds (they should turn easily when ready). Once turned, let cook for another 2 minutes on other side, until they're lightly browned and just opaque in the center.
During the last minute of grilling time, add the scallions to the grill and grill over direct heat, turning once.
Transfer the scallops to a clean bowl and add hot pepper sauce and the remaining 1 Tbsp melted butter and toss to coat.
Move scallions to cutting board and roughly chop.
Divide the grits among four plates. If they've solidified, you can loosen them with a few tablespoons of water or milk and continue to warm through.
Top grits with scallops, scallions and toasted panko.
Garnish with parsley and serve immediately with more hot pepper sauce, if desired.