Preheat oven to 450 F.
Place bones marrow side up into baking dish. If bones don’t stand up on their own, you can bunch up foil to keep them standing straight up and down. Place bones in oven for 15 minutes.
While the bones are cooking, wash and dry parsley leaves; discard stems. Slice baguette to 3/8” thick. Peel and finely slice shallots. Quarter and juice lemon.
Combine parsley, shallots, and capers in a salad bowl. Brush sliced baguette with olive oil and place on top rack of oven for 2 minutes, flip and repeat while marrow bones finish cooking.
Remove marrow bones from the oven and check to see if they are soft with a jelly-like consistency. Cook longer if needed, but avoid overcooking, as marrow will liquify and run out of the bones.
Mix lemon juice and olive oil into the parsley salad.
Serve marrow with salad and crusty bread. Spread marrow onto bread; top with salad and a sprinkle of salt.
3-4 Beef Marrow Bones
1 bunch parsley
2 tsps capers
1 French baguette
3 tbsps olive oil
Kosher salt to taste