Heat 1 tbsp extra virgin olive oil in a large skillet over medium-high heat. Season 500 g pork tenderloin with ½ tsp salt and ¼ tsp Freshly ground black pepper. Sear for about 3 minutes per side, turning until browned all over. Transfer to a plate.
Melt 2 tbsp unsalted butter in the same skillet. Add 2 shallots, chopped, remaining ½ tsp salt, and ¼ tsp Freshly ground black pepper. Cook for about 2 minutes, until softened.
Stir in 3 cloves garlic , minced, and cook for 30 seconds. Add 300 g cremini mushrooms, sliced, and sauté for about 4 minutes, until softened and golden.
Pour in 250 ml chicken broth and scrape the browned bits from the bottom of the skillet. Simmer for 5 minutes.
Stir in 300 ml heavy cream and simmer gently for 2 minutes, until the creamy mushroom sauce begins to thicken.
Slice the pork tenderloin into medallions and return them to the skillet. Cook for about 3 minutes, until the pork is cooked through and the sauce coats each piece. Serve hot.
Notes
Brown the Pork Evenly: I turn the tenderloin as it sears so every side develops a golden crust and adds more flavor to the sauce. Cook the Garlic Briefly: I give the garlic only 30 seconds in the skillet. This keeps it fragrant and prevents it from becoming bitter. Simmer the Cream Gently: Once I add the heavy cream, I lower the heat and avoid a rapid boil so the sauce thickens smoothly. Slice Before Finishing: I slice the pork before returning it to the skillet so the mushroom sauce coats every medallion.