Preheat oven to 400 degrees.Lay olives and tomatoes in a baking pan lined with parchment paper. Sprinkle with salt and oregano (canned olives are already salty so don't sprinkle more salt on them).Roast for 20 minutes or until the tomatoes burst and start to wrinkle.In a pot with a touch of oil, cook chickpeas with chilli powder and coriander powder on low heat (we are only trying to warm up the chickpeas and cook off the spices). Roughly chop cilantro and toss it in and squeeze in half a lime.With a potato masher (preferably), mash the chickpeas roughly making sure that a few still keep their shape. (Watch my video to see how I do it.) Remove from stove and keep aside.For the cheese base, mix ricotta cheese, cream cheese and sour cream in a bowl. Season with salt and pepper and set aside.Once toppings are ready, slice the bread into 1¼ inch thick diagonal slices. Brush olive oil on both sides of the bread and lay on a baking tray.Stick the tray under the broiler for two minutes on each side until both sides are toasted and nicely browned. Don't leave them unattended because they will burn! Ask me how I know.To assemble the Crostini, spread a generous amount of the cheese mixture, then top with your favorites toppings. Following are my favorite topping combinations:-Olives and tomatoes topped with parsley (I think of these as Greek)-Just tomatoes topped with basil (on the Italian side)-Spicy chickpeas topped with cilantro (Pakistani/Mexican flavor)Double the quantities to use an entire loaf. Enjoy!