Preheat the oven to 400°F (200°C). Line a baking sheet with parchment paper or place a wire rack on the sheet.
In one shallow bowl, whisk together the egg, Dijon mustard, Worcestershire sauce, and salt and pepper until smooth.
In a second shallow bowl, combine the whole wheat panko, grated Parmesan, flaxseed meal, dried thyme, garlic powder, and onion powder.
Working with one tender at a time, dip each chicken tenderloin into the egg mixture, letting excess drip off, then press into the breadcrumb mixture to coat evenly on all sides.
Arrange the coated tenders on the prepared baking sheet or wire rack, leaving space between pieces for airflow.
Lightly spray the tops of the tenders with cooking spray. Bake for about 20 minutes, flipping once halfway through, until golden brown and cooked through (internal temperature 165°F / 74°C).
Remove from the oven and serve immediately with your favorite dipping sauce.
