Preheat the oven to 375° F. Spray a baking sheet with nonstick spray or line with parchment paper.
Drain the liquid from a can of clams and discard; set aside.
Cut each slice of bread into quarters, set aside.
In a small frying pan, melt the butter. Then cook the parsley with the shallot until the shallot softens. Make a slight indentation in the middle of each piece of bread. Brush each piece of bread with olive oil, then put small amount of clams and then a small spoonful of the shallot/parsley mixture in the center of the bread.
Place all of the clam crostini on the prepared baking sheet and bake for 10 minutes. Serve at once, while still hot, with lemon wedges for squeezing.