Line a 9-inch square pan with aluminum foil; coat with cooking spray.
Bring 2 1/2 cups chicken broth and 2 cups milk to a boil in a large saucepan; stir in grits and salt. Reduce heat, and cook, stirring constantly, 17 to 20 minutes or until very thick. Stir in pepper to taste.
Spread hot grits evenly into prepared pan; let stand 10 minutes. Cut into 6 rectangles; cut each in half, forming 2 triangles. Serve immediately.