Prepare Creamy Shamrock Gelatin recipe. Prepare 1 package of gelatin: Dissolve gelatin in 2 cups of boiling water, stirring until completely dissolved; add 1 cup of cold water.
Pour approximately 1 1/2 cups of gelatin into lightly oiled pan (just enough to fill shamrock area of pan). Chill until set but not firm.
Meanwhile, dissolve remaining two packages of gelatin in 4 cups of boiling water. Add remaining gelatin from first package; allow to cool. When cool, blend 2 1/2 cups of sour cream into cooled mixture and spoon over gelatin in mold. Chill until set; unmold.