Heat oven to 200C/180C fan/gas 6.
Heat the oil in a large frying pan and cook
the onion, garlic and 2 tsp of the herbs
for 3 mins until starting to soften. Add
the turkey and brown all over, then tip in
the tomatoes and cook for 5 mins more.
Scoop out the middle of the marrow
and discard (or fry, then freeze for
another time – try it mashed with potato).
Arrange the slices in a baking dish. Spoon
the mince into the middle of each
marrow slice, then spoon the rest over the
top. Cover with foil and bake for 30 mins.
Meanwhile, mix remaining herbs with
the breadcrumbs and Parmesan. Remove
the marrow from the oven, uncover, and
sprinkle over the crumbs. Return to the
oven for 10 mins more until crumbs are
golden and crisp and marrow is tender.