In a large bowl, cream together the butter and white sugar until smooth. Beat in the eggs one at a time until each is blended in. Stir in the vanilla.
Combine the flour, baking soda, and salt; stir into the creamed mixture, alternating with the buttermilk, mixing just until blended. If the dough is really sticky, you may need more flour. Cover and refrigerate for 1 hour.
Preheat the oven to 350 degrees F (175 degrees C). On a lightly floured surface, roll the dough out to 1/4 inch thickness.
Cut into squares and rectangles using a pizza cutter or knife.
Place cookies about 2 inches apart on ungreased cookie sheets.
Bake for 6 to 8 minutes in the preheated oven, until the edges begin to brown lightly.
While the cookies are baking, make the frosting. In a medium bowl, beat the cream cheese and confectioners' sugar until soft and creamy. Stir in the whipped topping until well blended.
Spread a thin layer of the frosting onto each cookie. Make heart cards by placing strawberry slices onto the rectangular cookies, and dice by placing blueberries onto the square cookies. Refrigerate until serving, or serve immediately after frosting. They are best when served cold.
