In a food processor fitted with the steel blade, blend the cottage cheese and milk just until smooth. Add the scallions, salmon, cream cheese, lemon juice, and a pinch of white pepper. Process until smooth and creamy. Refrigerate for 1 hour.

While the salmon filling is chilling, cut the cucumbers into ¾-inch thick rounds, discarding the ends. Using a small spoon, scoop the seeds and some of the flesh out of each round to form a small cup.

Fill each cup with about 2 teaspoons of the salmon filling and sprinkle with the chives. Cover and refrigerate until ready to serve, up to 1 hour.