Preheat oven to 450 degrees with rack in the middle of the oven. Lay the slices in a glass dish and pour the marinade over them. Set aside while preparing the bread.
Slice bread lengthwise with a serrated knife to create a top and bottom.
Spread half of the garlic herb butter on the cut surface of each half of the bread. Place bread, cut side up, on a sheet pan. Place in the oven for 3-4 minutes until the bread is lightly toasted. Remove from oven. Lift tomato slices from the marinade and drain.