Make a large groove in the middle of the fillet and fill it with the speculaas paste. Rub the meat with some oil, herbs, and salt and pepper, and grill it over a moderate fire. The meat is best when still pink on the inside. Combine the veal stock, white wine and sage leaves.
Bring to a boil and reduce to 2/3 of the original volume. Thicken with a lump of cold butter. Cut the meat into slices. Finish with speculaas cookie crumbs.
Tip: Make your own speculaas paste. Mix 50 g softened butter, 30 speculaas cookies, 2 tbsp candied syrup/liquid cane sugar into a homogenous mass. Peanut butter is also a good substitute for speculaas paste.