Preheat your oven to 375°F. Line a baking sheet with parchment paper or lightly grease it.
In a shallow bowl, combine the finely chopped walnuts, breadcrumbs, garlic powder, onion powder, salt, and black pepper. Mix well to combine.
In another bowl, whisk together the egg and Dijon mustard until smooth.
Dip each chicken breast into the egg mixture, allowing any excess to drip off. Then, coat the chicken in the walnut mixture, pressing gently to ensure it adheres well.
Place the coated chicken breasts on the prepared baking sheet. Drizzle the olive oil over the top of each piece.
Bake in the preheated oven for 25-30 minutes, or until the chicken is cooked through and the coating is golden brown. The internal temperature should reach 165°F.
Let the chicken rest for 5 minutes before slicing and serving.
Notes
For added flavor, try adding a teaspoon of dried herbs like thyme or rosemary to the walnut mixture.
If you prefer a spicier kick, add a pinch of cayenne pepper to the coating.
Serve with a side of roasted vegetables or a fresh salad for a complete meal.