Place raw marrow bones on a baking sheet lined with foil (for easy clean up). Sprinkle each bone with a pinch of coarse sea salt.
Roast bones for about 20-25 minutes. The marrow should be soft all the way through, with a little marrow leaking out in the bottom of the pan.
Insert a skewer or small knife in the middle - it should go through very easily, like warm butter.
Remove and let them rest for about 5 minutes or until cool enough to touch.
Scoop out with a small knife and spread on toasted bread. Sprinkle with a little more sea salt (to taste) and serve.
Bone Marrow Butter:
Mix 2 tablespoons of bone marrow with ½ stick softened unsalted butter. Add about ¼ to ½ teaspoon salt in mix everything together until a compound butter forms. Adjust the salt to taste.You can also mix in truffle zest, fresh herbs, roasted garlic, etc.
Roll it up in a log shape in plastic wrap and store it in the fridge for 2-3 days, or the freezer for up to 6 months.
Notes
This recipe can be easily doubled, tripled, or made to accommodate any number of people. Just use a larger pan and roast using the same instructions.
Soaking the marrow bones helps to remove blood and impurities from the bones. I don't recommend skipping this part.
The marrow should be hot and ultra tender in the center - a knife should go right through it like warm butter.
When seasoning, just use your fingers to pinch a touch of flaky sea salt and sprinkle it on top after spreading it on the toast.
Make sure you don't overcook it as it will liquify if it is cooked too long.
Some bones have more marrow than others, so keep that in mind if you're planning appetizers and make an extra couple just in case.
The internal temperature should be 145°F when done cooking.