Preheat oven to 425 degrees F. Line a large rimmed baking sheet with parchment paper.
Combine mustard, garlic, lemon zest, lemon juice, rosemary, honey, salt and crushed red pepper in a small bowl. Combine panko, walnuts and oil in another small bowl.
Place salmon on the prepared baking sheet. Spread the mustard mixture over the fish and sprinkle with the panko mixture, pressing to adhere. Lightly coat with cooking spray.
Bake until the fish flakes easily with a fork, about 8 to 12 minutes, depending on thickness.
Sprinkle with parsley and serve with lemon wedges, if desired.