Cucumber and Watercress Sandwich Appetizers

Ingredients (8)

• + 8 cups cucumber, peeled and finely chopped add to pantry
• + 1 teaspoon salt add to pantry
• ✓ ¼ teaspoon ground black pepper
• + ¼ cup chopped fresh chives add to pantry
• + ⅔ cup butter, softened add to pantry
• + 20 slices whole wheat bread, crusts removed add to pantry
• ✓ ⅓ cup mayonnaise
• + 2 cups trimmed and coarsely chopped watercress add to pantry