Place ?1/2cupunsalted butter, ?4ouncescream cheese, ?1/2teaspoonvanilla extract, and ?1/4cupsugar in a food processor or standing mixer and mix until smooth and combined.
With the mixer running on low, slowly add ?1cupall purpose flour a little at a time until the dough just comes together; do not overmix.
Divide the dough into 2 equal balls, wrap each ball in plastic wrap, and refrigerate for 1 hour.
While the dough chills, combine ?1/4cuppreserves and the filling ingredients (?1/4cupchopped walnuts or pecans, ?1/4cupchopped dried fruits, ?1/4cupmini chocolate chips) in a bowl and stir to mix evenly.
Preheat the oven to 350°F.
On a lightly floured surface, unwrap one dough ball and roll it into a 9-inch round. Repeat with the second dough ball.
Use a pizza cutter or knife to cut each 9-inch round into 8 equal wedges (like slicing a pizza), for a total of 16 wedges.
Spread 2 tablespoons of the ?1/4cuppreserves on each round (so each round gets 2 tablespoons). Divide the mixed filling from step 4 evenly between the two rounds and sprinkle it over the preserves, leaving a small margin at the outer edge.
Starting at the wide end of each wedge, gently roll the wedge toward the tip to form a crescent; roll all 16 wedges.
Place the rolled rugelach on a baking sheet with the pointed tip tucked underneath (tip pointing down) to help prevent unrolling.
If using the optional egg wash, lightly beat the ?1egg and brush the tops of the cookies.
Bake at 350°F for 20–25 minutes, or until the rugelach are golden brown.
Remove from the oven and let cool on the baking sheet a few minutes, then transfer to a wire rack to cool completely.
Notes
11. If using the optional egg wash, lightly beat the ?1egg and brush the tops of the cookies.