Whisk all glaze ingredients in a saucepan. Simmer over medium heat for 8 to 10 minutes until thick enough to coat a spoon. Set aside.
Pat salmon fillets completely dry. Season both sides with salt and black pepper. Rest at room temperature 10 to 15 minutes.
Heat grapeseed oil in a cast-iron pan over medium-high. Place fillets flesh-side down. Sear for 3 to 4 minutes without moving until a golden crust forms.
Flip each fillet to skin-side down. Brush whiskey glaze generously over the top immediately.
Transfer pan to a preheated 450°F oven. Cook 3 to 4 minutes until the glaze caramelizes and the internal temperature reads 125 to 130°F.
Remove from oven. Brush with one final coat of glaze. Rest 2 minutes before plating with parmesan mashed potatoes, roasted carrots, and grilled baby broccoli.