Ingredients
1/2  pound flaked cooked crab meat or flake-style imitation crab meat
1  3-ounce package cream cheese, cut up and softened
2  tablespoons mayonnaise
1  tablespoon Dijon-style mustard
1  tablespoon minced shallots
2  teaspoons prepared horseradish
1/2  teaspoon ground cayenne pepper
1/4  teaspoon salt (optional)
4  medium cucumbers, each about 8 inches long

Directions
1. Remove 2 tablespoons crab meat for garnish, if desired. Place remaining crab or imitation crab, cream cheese, mayonnaise, mustard, shallots, horseradish, pepper, and salt, if using, in a food processor bowl; cover and process until smooth, scraping sides of bowl. Spoon mixture into a pastry bag fitted with a large star tip.
 
2. Using a zester or vegetable peeler, peel the cucumbers, leaving some strips of skin. Cut into 3/4-inch-thick slices. (Or, halve 2 cucumbers lengthwise and slice 3/4-inch thick.) With a melon baller, scoop out the center of each slice to create a cup. Pipe mousse into cucumber cups. Sprinkle each with reserved crab meat, if desired. Cover and chill up to 2 hours before serving. Makes about 40 pieces. 

Source:  Better Homes & Gardens