Cut the butter into small chunks. Add the butter and cream cheese to the bowl of a stand mixer fitted with a paddle attachment. The butter and cream cheese should be taken directly from the refrigerator prior to use. You want to work with them while they are cold. Mix them together until combined and smooth, about 2 minutes (be sure to scrape the sides and bottom of the bowl as needed).
Remove the paddle attachment from the mixer.
Add the flour, potato starch, and powdered sugar to the bowl. Using your hands and NOT the mixer, lightly mix the ingredients together. You want the dough to come together by simply using your fingertips to turn the dough over repeatedly.
Once all of the dry ingredients are incorporated into the butter, you can lightly press the dough together into a small rectangle. Wrap the dough in plastic wrap and refrigerate for 30 minutes.
Dust a hard surface with a tablespoon of powdered sugar. Unroll the dough and lightly dust the top of the dough and a rolling pin with powdered sugar (about 1 tablespoon). Roll the dough out into a rectangle that measures 13" x 10". If the edges are very jagged you can trim them off with a knife.
Place the cherry preserves and one teaspoon of flour into a small bowl. Stir together. Spread onto the dough leaving a 1/2" border all the way around.
Now, roll up the dough. You want to begin at one long end and roll snuggly. It you leave too much space and opt to roll the dough loosely, you will have air gaps in your rugelach. So roll snuggly but not so tight that all of the filling squishes out. Once the roll comes together trim 1/2" off of each end. Discard. Wrap the roll in plastic wrap and place in the freezer for 20 - 30 minutes until just firm (not frozen).
Preheat the oven to 375 degrees.
Line a standard baking sheet with parchment paper.
Unroll the dough and using a serrated knife, cut into 12 equal pieces. I like to cut the roll in half first, then cut 6 slices from each half. Place each cookie onto the baking sheet leaving at least 2 inches between each. The swirled sides should be facing outward.
Brush the tops with a bit of cream.
Bake for 15-17 minutes or until golden brown.Allow to cool for 30 minutes before eating.If desired, place 1/4 cup of powdered sugar into a handheld sifter and dust the cookies.