Let’s walk through preparing this Beef Tenderloin in a simple, step-by-step way. Start by getting all your tools ready, like a good pan and a meat thermometer, to make things go smoothly. You’ll preheat your oven to 120°C/250°F for that even cook we all want.

First, pat the beef dry with paper towels and sprinkle it evenly with 1 1/2 teaspoons cooking or kosher salt and 1/2 teaspoon black pepper. Pop it on a rack in a tray and let it chill in the fridge uncovered for 12 to 24 hours if you can it really amps up the flavor.

Next, mix up the garlic-thyme-butter slather in a bowl. Combine 75 grams (5 tablespoons) of softened unsalted butter with 1 teaspoon finely grated or minced garlic, 1 teaspoon fresh thyme leaves (chopped), 1/4 teaspoon cooking or kosher salt, and 1/4 teaspoon black pepper. This step adds a burst of herbs that makes the beef extra tasty.

Take the beef out of the fridge about 2 hours before cooking to let it warm up. Then, heat 1 tablespoon vegetable oil in an ovenproof heavy pan over high heat until it’s smoking. Sear the beef on all sides until it’s nicely browned and let it cool for 15 minutes on the rack.

Once cooled, put the beef back in the skillet and spread about three-quarters of the garlic-thyme butter over the top and sides. Roast it in the oven for 15 minutes, then add the rest of the butter and roast for another 25 to 35 minutes until it hits 53°C/127°F inside for medium-rare.

After roasting, let the beef rest for 10 minutes this helps it reach about 56-58°C (133-136°F) and keeps it juicy. For the sauce, pour the juices from the skillet into a bowl and spoon off 1/4 cup of the fat to return to the skillet, saving the rest.

Heat that fat over high heat, add 150 grams (5 oz) of sliced white mushrooms, and cook until they sweat. Toss in 1 thyme sprig and 1/2 teaspoon minced garlic, cooking for 2 more minutes until soft. Then, add 1/2 cup low sodium chicken stock and reduce it by half.

Follow that by adding 3/4 cup Marsala or a substitute and reduce by half again. Stir in 3/4 cup thickened cream, 1/4 teaspoon black pepper, and the reserved juices, simmering for 5 minutes until it thickens. This sauce pairs perfectly with your sliced beef, adding a creamy touch.