Beef Wellington Parcels With Red Wine Jus - With greens

2 ounces unsalted butter , diced and chilled, plus extra for greasing 2 tablespoons olive oil , for frying 1 large onion , finely chopped 2 garlic cloves ,[...]

3 1/2 lbs beef tenderloin fillets salt pepper garlic powder basil 1 package garlic and harbs boursin cheese 8 ounces mushrooms , chopped 1 lb puff pastry[...]