Cookies:
 

1. Beat cream cheese, butter, sugar and salt together until smooth with no lumps, about two minutes. Beat in egg yolks, vanilla and lemon juice until fully combined. Add flour and mix until just incorporated without over-mixing.
2. Cover bowl of dough and refrigerate for at least two hours. During the last 30 minutes of chill time, prepare filling.

Filling:

1. Beat cream cheese, butter, both sugars, vanilla, sour cream and milk together until completely smooth. Optional: spoon mixture into a plastic bag and cut a corner off for ease when filling cookies.
2. Preheat oven to 350°F and line two baking sheets with parchment paper. Remove dough from refrigerator and roll about 1 tablespoon of dough each into balls and place on prepared baking sheet.
3. Make an indentation in the center of each ball of dough. Pipe 1/2 teaspoon of cream cheese mixture into the center of each cookie.
4. Bake cookies for 11-12 minutes - they should be very lightly golden on the bottoms.

Glaze:

1. In a small bowl, whisk all glaze ingredients together. Remove cookies from oven and allow them to cool for 5 minutes on the hot pan before transferring them to a wire rack to finish cooling completely. Drizzle glaze on cooled cookies.