Set your oven to 375°F and prepare a rimmed baking sheet by lightly coating it with cooking spray or oil.
In a large shallow dish, pour the buttermilk over the chicken tenders, ensuring they are fully coated.
In a separate shallow dish, mix the chopped walnuts, whole-wheat flour, fresh thyme, cayenne pepper, a pinch of kosher salt, and freshly ground black pepper.
Take each chicken tender, one at a time, and coat it in the walnut mixture, pressing gently to ensure the coating sticks. Lay the coated chicken pieces on the prepared baking sheet, spacing them evenly. Lightly brush or drizzle them with olive oil.
Place the chicken in the oven and bake for 15 to 20 minutes, or until the crust is golden brown and the chicken is fully cooked through.
As the chicken cooks, prepare the honey sauce by combining the honey and Dijon mustard in a small saucepan. Heat over medium heat for about 2 minutes, stirring, until the sauce becomes warm and smooth.
When the chicken is done baking, take it out of the oven and drizzle half of the honey sauce over the top. Place a small wedge of Brie cheese on each piece of chicken, then return the baking sheet to the oven for an additional 3 to 5 minutes, allowing the Brie to melt.
Remove the chicken from the oven once the Brie has melted and serve immediately. Drizzle the remaining honey sauce over the chicken for a finishing touch.