Using an electric mixer on medium speed, beat the butter and cream cheese until light and creamy. Add the flour and salt, and beat until blended. Cover the dough and chill 1 hour.
Preheat oven to 325°F (160°C). Lightly grease 24 mini muffin cups.
Shape the dough into 24 1-inch balls. Place 1 ball in each cup of the mini muffin pan. Press the dough firmly into the bottom and up the sides of each muffin cup, making sure the crust isn’t too thin. A slightly thicker crust will help the tarts hold together after baking.
Spoon 1/2 teaspoon preserves into the bottom of each tart.
Stir together the egg, sugar, and crumbled almond paste. Spread the filling evenly over the raspberry preserves so each tart has a consistent layer. This helps the tarts bake evenly and keeps the crust from becoming too fragile. Sprinkle with chopped almonds.
Bake 25-30 minutes, or until golden brown.
Allow the tarts to cool completely in the pan before removing them. The crust firms up as it cools, which helps the tarts hold their shape. If needed, run a thin knife around the edge of each tart before removing it from the pan.
Notes
Store the tarts in an airtight container at room temperature for up to 3 days. They can also be frozen for up to 1 month. Thaw at room temperature before serving.