Step 1- Acquire beef bones (marrow bones, joints, etc) from a processor, grocery store or a farmer. I can usually get marrow bones cut in 4-6″ lengths.
Step 2- Lay them out on a baking pan that has some depth to catch the fat drippings.
Step 3- Bake at 400 deg F for 30-45 mins until fat is finished pooling up in the pan.
Step 4- Pour rendered fat into a your favorite butter dish, stick in the fridge to let it cool. Scoop out the cooked marrow inside the bones and do whatever with it.
Step 5- Eat like butter. Easier to digest (for me) than butter or rendered tallow, and even tastes kind of buttery in my opinion. Finished color is slightly yellow too.