Heat the olive oil in a small casserole, add the onion, and cook slowly until the onions are transparent and melting away. Add the garlic, stir, and add the olives and cook for 2 minutes. Stir in the saffron, the tomato paste, the wine and the fish broth. Cook for 5 minutes to bring the flavors together before pouring the whole mixture into a preheated earthenware dish (a Spanish cazuela), add the squid to the dish, give 1 more stir to combine and put the whole dish into the oven for 35 to 40 minutes.
Remove from the oven, taste and adjust the seasoning with salt and pepper and serve with Spanish bruschetta.