In medium saucepan combine pumpkin, 1/2 cup of sugar,cinnamon and egg yolks. Mix thoroughly. Add milk gradually to this mixture. Cook, stirring constantly, on medium heat, until mixture becomes thick. (You may prefer to use a double boiler)
Meanwhile mix package of gelatin in 1/4 cup hot or boiling water. Pour this into thick mixture of pumpkin. Set aside and allow to cool.