In your mixer's bowl, beat cream cheese and butter until smooth, light and fluffy.
Add flour and salt and continue to mix until thoroughly combined.
Lightly dust work area with powdered sugar.
Transfer dough to work area and shape into a ball.
Divide it into 4 rounds; flatten each round and cover each pastry dough with plastic wrap.
Refrigerate for 30 minutes.
In the meantime, prepare the filling by combining cream cheese, powdered sugar and vanilla in your mixer's bowl.
Beat until creamy and smooth. Set aside.
Dust work area with flour.
Remove dough from fridge and let rest for 5 minutes.
Roll out each ball of dough to a 1/4-inch thickness.
Cut into 3x3 squares.
Fill the center of each square with 1/2-teaspoon cream cheese mixture and 1/2 teaspoon strawberry jam. For a prettier presentation, using a pastry bag, you can pipe the fillings, one on top of the other.
Overlap opposite corners of dough to the center and over the filling. Pinch seams together.
Refrigerate for 1 hour.
Preheat oven to 375.
Bake 10 to 11 minutes, or until edges are browned.