Put oven rack in middle position and preheat oven to 350°F.
Toast pecans in a shallow baking pan until fragrant and a shade darker, about 10 minutes. Toss hot pecans in pan with butter and salt, then cool.
Coarsely chop nuts, then toss together with cheese in a bowl, without mashing.
Top each cracker with a mounded teaspoon of cheese mixture, pressing together slightly, then top with a parsley leaf and a grape half, gently pressing them into cheese.
