Preheat your oven to 375°F (190°C).

In a dry skillet over medium heat, toast the fennel seeds until fragrant, about 2-3 minutes. Remove from heat and allow to cool.

In the same skillet, add the cardamom pods and toast for an additional 2-3 minutes until fragrant. Remove from heat, allow to cool, and then crack the pods open to extract the seeds.

In a spice grinder or mortar and pestle, combine the toasted fennel seeds and cracked cardamom seeds. Grind to a coarse powder.

Rub the veal loin roast with olive oil, then generously season with salt and freshly ground black pepper. Coat the roast with the fennel and cardamom mixture, pressing it firmly into the meat.

Heat a large oven-safe skillet over medium-high heat. When hot, sear the veal roast on all sides until browned, about 3-4 minutes per side.

Once seared, transfer the skillet to the preheated oven and roast the veal until it reaches an internal temperature of 145°F (63°C) for medium-rare, about 20-30 minutes.

While the veal is roasting, prepare the caramelized leek butter. In a separate skillet, melt the unsalted butter over medium heat. Add the sliced leeks and season with salt. Cook the leeks slowly, stirring occasionally, until they are golden and caramelized, about 15-20 minutes.

Once the leeks are caramelized, add the fresh thyme leaves and the chicken or veal stock to the skillet. Simmer for an additional 5 minutes, allowing the flavors to meld. Adjust seasoning with salt and pepper as needed.

When the veal roast is done, remove it from the oven and let it rest for 10 minutes before slicing.

Serve the sliced veal loin roast drizzled with the caramelized leek butter.