Preheat oven to 325 degrees F (160 degrees C) grease and flour a 10 inch tube pan.
In a large bowl, cream butter and cream cheese until smooth. Add sugar gradually and beat until fluffy.
Add eggs two at a time, beating well with each addition. Add the flour all at once and mix in. Add vanilla.
Pour into a 10 inch tube pan. Bake at 325 degrees F (160 degrees C) for 1 hour and 20 minutes. Check for doneness at 1 hour. A toothpick inserted into center of cake will come out clean.
For your Lemon Curd Sauce: Place the sugar and cornstarch in a medium saucepan. Whisk in the water. Place the pan over medium-high heat and cook, whisking constantly, until the mixture just begins to boil, 4-5 minutes. Remove the pan from the heat.
Using a fork, lightly beat the egg in a small mixing bowl. Spoon in 2 tablespoons of the hot sugar mixture and beat vigorously with the whisk to incorporate. Spoon in another 2 tablespoons of the hot mixture and beat vigorously again.
Place the saucepan back over medium heat, and pour the beaten egg mixture into the pan, whisking constantly. Let the mixture boil for 1 minute, whisking. The mixture will be thick. Remove the pan from the heat, and stir in the butter, lemon zest, and lemon juice until they are incorporated.
Spoon this warm sauce over cake or ice cream.
Store this warm lemon curd sauce in a glass jar in the refrigerator for up to two weeks. Reheat it on top of your stove over low heat or in the microwave for 1-2 minutes.
Recipe by MomAdvice at http://momadvice.com/blog/2012/02/cream-cheese-pound-cake-with-warm-lemon-curd-sauce