6 to 8 beef marrow bones cut in 2- to 3-inch tubes open on both ends
8 Tbsp. butter, removed from fridge a few minutes prior, cubed
Ό Tbsp. rosemary, chopped fine
Ό tsp. fleur de sel
Ό tsp. freshly ground black pepper
Soak the bones overnight in salted ice water to clean out impurities.
Pat the bones dry.
Preheat the oven to 425 degrees.
Roast the bones for 15 minutes. Check them and cook for another 5 minutes, or until marrow is just cooked through (it should look bubbly and be knife-tender). Save all the fat that renders out. If the bones cook too long, all the marrow will render. This fat is still good to make the butter.
Let the bones cool enough to handle, or chill if time permits. Push the marrow out of the bones. If the marrow still appears somewhat raw after its been pushed from the bone, heat it gently in the rendered fat until cooked. This should produce approximately ½ cup of marrow.
Combine the marrow with all other ingredients in a food processor and pulse to incorporate. Chill.
Whip the marrow butter to increase volume, then roll into logs and chill.
* Use with lean meats such as bison, roast lamb or roast beef. Also try it on a grilled cheese, spreading it on the bread in lieu of regular butter.