1. In a large skillet, cook the bacon over medium heat, turning occasionally, until browned and crisp, about 8 minutes. Drain on paper towels.
2. While the bacon cooks, pat the scallops dry and sprinkle with the salt and cayenne. To the bacon fat in the pan, add the butter and turn the heat to high. When the butter foam subsides, add the scallops in a single layer. Cook, turning once, until nicely browned and just opaque throughout, about 2 minutes. Transfer to a plate.
3. Drain any remaining fat from the skillet. Add the Crown Royal® Maple Finished Whiskey and boil, stirring and scraping the browned bits from the pan, until reduced to 3 tablespoons, about 5 minutes. Stir in the sugar until the mixture becomes syrupy and thick, about 1 minute, then turn the heat to low. Break each strip of bacon in half and add to the syrup. Cook, turning, until well coated and caramelized.
4. On each apple slice, stack a scallop and a piece of bacon. Garnish with red onion slices and serve.