Preheat oven to 350°. Place the first 6 ingredients (through marjoram) in a food processor; pulse until coarsely ground.
Arrange 4 pita halves, rough sides up, on a baking sheet. Brush with 2 tablespoons oil. Spread 4 teaspoons pistachio mixture over each pita half. Bake at 350° for 16 minutes, or until lightly browned and crisp. Repeat with remaining pita halves. Cool. Break each half into 4 pieces; serve with Feta-Peppercorn Spread and red grapes.