Wash the prunes and drain well. Wash the meat and dab dry. Tie a loop around the roast at one end with kitchen string. Then tie the roast like a package so that it keeps its shape.
Make a small incision on one narrow side of the roast. Then drill a hole through the roast with a sharpening steel or a wooden spoon handle. Fill it with plums on both sides and push it through with a wooden spoon.
Rub the roast with salt, pepper and marjoram. Heat butter and oil in the roaster. Brown the roast all around. Take it out. Stir the wine and cream into the roaster. Put the roast back in. Cover and cook in a preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: level 2) for about 1 1/4 hours.
Remove the lid and cook the roast for another ten minutes, so that it gets a nice crust. Take the roast out and remove the kitchen string. Season the sauce with salt and pepper. Serve with apple red cabbage and boiled potatoes.