Slice the bread or baguette up. Although it's recommended to use fresh french baguette or fresh Italian bread, given that the Crostini's history any bread would do.
Place the slices onto the middle wire rack under a highest set temperature broiler in the oven. Toast until golden brown spots/lines start to appear around the edges or randomly on top.
Flip the slices over then keep toasting until golden brown spots start to overwhelm the bread.
Check the other side and flip the Crostini slices again if necessary to achieve the same golden brown color on both sides. This method yields slightly softer textured Crostini slices, for harder pieces use more time with bottom and top heater turned on at lower temperature about 400°F / 200°C.
Let them cool off a bit then top them up with whatever ingredients we have at hand.
Enjoy!