Using a large chef’s knife or carving knife, slice roast lengthwise, stopping when you are about ½ inch (1 cm) from bottom of the roast. Open the roast up like a book and cut one side to “unroll” the roast to be about ¾ inch (2 cm) thick piece of meat. Do the same with the other side so that you end up with a rectangular piece of meat that is about 3/4 inch (2 cm) thick. Using a flat meat mallet, pound the roast to about ½ inch (1 cm) thickness; set aside.
Sprinkle the cheese evenly over the flattened roast.
Next spread the cooled stuffing on top of the cheese.
Roll it up like a roulade (or jelly roll) and tie with kitchen string at 2-inch (5 cm) intervals. Slide a spring of rosemary under the strings to create a wonderful aroma while cooking. Place on a rack on a shallow roasting pan or sheet pan. Brush entire roast lightly with olive oil and season with salt & pepper.
Cook for 1 hour until internal meat temperature reaches 125°F. Remove from oven.
Heat a tablespoon of olive oil in a large cast iron or heavy bottom pan until beginning to shimmer. Add the roast and sear all sides for 60 - 90 seconds (each side) until nicely browned.
Return the roast to the roasting rack and lightly tent with foil, leave to rest for 10 minutes before carving.
Serve 2.5 cm (1/2 inch) slices of beef with mushroom gravy, garnished with thyme & rosemary sprigs.