Step 1: In a large bowl with an electric mixer, cream together the softened unsalted butter and softened cream cheese until light and fluffy, about 2-3 minutes. Beat in the almond extract and salt.
Step 2: Gradually add the all-purpose flour, mixing on low speed until just combined and a soft dough forms. Do not overmix. Divide the dough into two equal portions, flatten each into a disk, wrap tightly in plastic wrap, and refrigerate for at least 2 hours, or preferably overnight, until firm.
Step 3: Preheat your oven to 375°F (190°C). Lightly flour a clean work surface and your rolling pin. Take one disk of chilled dough from the refrigerator. Roll the dough out to about ⅛-inch thickness. Using a sharp knife or pizza cutter, cut the dough into 2-inch squares.
Step 4: Place about ¼ to ½ teaspoon of your chosen thick jam in the center of each dough square. Fold two opposite corners of the dough over the jam, pinching them together firmly to seal. You can also dab a tiny bit of water on the corners before pinching to help them stick. Arrange the shaped cookies about 1 inch apart on baking sheets lined with parchment paper.
Step 5: Bake for 12-15 minutes, or until the edges are lightly golden. The cookies should still be soft in the center. Transfer the cookies to a wire rack to cool completely.
Step 6: Once cooled, generously dust the Kolaczki with powdered sugar before serving. Store in an airtight container at room temperature.