Remove the bone marrow. To do this, press the marrow with your thumb so as to push it out of the bones. If the marrow is stuck, warm the bones in a 180 °C (350 °F) preheated oven for 8 to 10 minutes and press again. If necessary, remove with a small knife. Cut the marrow into 1-cm (1/2-inch) thick slices. Set aside.