Chaeaubraind

Butterfly loin from bottom 1/3 and then butterfly again to make one large ’sheet’ of meat, return to refrigerator. Saute butter, olive oil, onion, salt, and pepper in non-stick pan for 5 minutes on medium-high. Pulse mushrooms in food processor with eight one second pulses. Add mushrooms to cooked onion mixture. Cook for 5 minutes more then reduce to medium low. Add garlic and madera. Reduce in pan 2-3 minutes more. Transfer to plate and spread out to thin layer to cool. Spread cooled stuffing on loin leaving 1/2" around edge of meat. Press spinach onto surface of loin stuffing evenly. Roll loin into itself and tie with butcher string. Rubb loin with olive oil, coarse pepper, and coarse salt. Let sit at room temperature for 1 hour. Sear in skillet with some oil. Brown each of four sides for 2-3 minutes each. Put on rack on sheet pan then place in oven at 450 F for 20-25 minutes (Internal temperature of 120 Rare - 125 Medium Rare). Remove from oven and slather with herb butter (see recipe) tent with foil, let stand for 15 minutes