Finely chop the olives. Peel and chop garlic. Mix with the olives and 1 tablespoon of oil. Scald tomatoes hot and peel the skin. Quarter tomatoes, remove seeds and cut flesh into small cubes.
Wash the crabs and dab them dry. Wash basil, dab dry, pluck leaves from the stalks and cut into strips. Mix tomatoes, crabs and basil. Season with salt and pepper. Cut baguette into about 20 slices and fry in the remaining hot olive oil on both sides until golden brown.
Brush with olive paste and spread tomato-crab mixture on top.