Preheat your oven to 375°F (190°C). Season the chicken breasts with salt and pepper on both sides.

In a medium bowl, combine the grated Parmesan cheese, garlic confit (mashed into a paste), black truffle oil, and fresh thyme. Mix until well blended.

Place the seasoned chicken breasts in a baking dish. Spread the Parmesan and garlic mixture evenly over the top of each chicken breast.

Bake the chicken in the preheated oven for about 25-30 minutes, or until the chicken is cooked through and reaches an internal temperature of 165°F (74°C). The cheese should be golden and bubbly.

While the chicken is baking, heat vegetable oil in a deep pan over medium-high heat. Dredge the sliced leeks in flour, shaking off any excess.

Once the oil is hot, carefully add the floured leeks in batches, frying until golden brown and crispy, about 3-4 minutes. Remove with a slotted spoon and drain on paper towels. Season lightly with salt.

Once the chicken is done, remove it from the oven and let it rest for a few minutes. Serve the chicken topped with crispy leek hay and garnish with fresh parsley.