Beat 4 oz of cream cheese, butter or margarine, and 2/3 cups sugar until fluffy.
Add the flour and mix until it comes together into a dough.
Roll the dough into roughly 1 inch balls. Place them on a parchment or silicone lined baking sheet. Use a thumb or the back of a measuring spoon to create a well in the center of the balls.
In a separate bowl, mix the remaining 4 oz of cream cheese, 1/3 cup of sugar, and the lemon juice or vanilla extract. Beat until smooth and creamy.
Drop about 1 tsp of the cream cheese filling into the wells in the cookie balls.
Bake the cookies at 350° for 10-12 minutes, or until the filling is set.
Leave the cookies on the sheet for 5 minutes, then transfer to a wire rack to cool. Store cookies in an airtight container in the refrigerator for up to 3 days.