Prep oven and baking sheet: Preheat your oven to 400°F (200°C). Line a rimmed baking sheet with parchment paper or foil lightly misted with olive oil spray.
Season salmon: Pat salmon fillets thoroughly dry on both sides with paper towels. Arrange fillets skin-side down on the prepared baking sheet, leaving about 2 inches between them. Season tops lightly with salt and black pepper.
Brush with Dijon: Spread about 1/2 tablespoon of Dijon mustard evenly over the top of each salmon fillet. This acts as a savory flavor foundation and glue for the crunchy topping.
Make the parmesan herb crust: In a small bowl, mix together the panko breadcrumbs, freshly grated Parmigiano-Reggiano, minced garlic, melted butter, chopped parsley, dill, lemon zest, and a pinch of salt until the breadcrumbs are evenly moistened and fragrant.
Top fillets generously: Spoon the parmesan panko mixture evenly over the mustard-brushed fillets. Use clean hands to gently press the topping onto each fillet so it adheres in a thick, even crust.
Bake to crispy perfection: Bake at 400°F for 12 to 14 minutes, depending on fillet thickness, until the salmon flakes easily with a fork and reaches an internal temperature of 125°F-130°F (52°C-54°C) for medium tender. For an extra golden crust, switch the oven to BROIL on high for the final 60 to 90 seconds, watching carefully so it does not scorch.
Garnish and serve: Remove from oven, squeeze fresh lemon juice over the crispy crust, garnish with extra fresh dill sprigs, and serve immediately while piping hot and crunchy.