Preheat the oven to 350 degrees. Line two baking sheets with parchment paper. Set aside.
In a mixer, cream the butter, shortening and sugar together until fluffy, about 3 minutes. Add in the egg and vanilla and beat until well combined.
In a small bowl, stir together the flour, baking powder, baking soda and salt. Alternate adding the flour mix and the sour cream to the egg mixer and then stir until you have a soft dough (it should look like sugar cookie dough).
Roll the dough into 1 inch balls then roll each ball in the nuts to coat them. (Tip: wet hands will keep the dough from sticking to you as you roll them up). Place the cookies two inches apart on the prepared pans. Using a wooden spoon handle or your pinky (or your thumb if you have tiny handmake a ½ inch deep indent in the middle of each cookie. Fill the indent with preserves and then bake for 15-20 minutes or until the cookies are lightly brown. Remove to a wire rack to cool.