• Make the dough: Place the flour, sugar, and salt in the bowl of a food processor fitted with a metal blade. Pulse a few times to combine. Add the chunks of butter, cream cheese, and egg yolk. Process until the dough starts to come together into a well-moistened, crumbly mass, 20 to 30 seconds. Transfer the dough to a clean work surface. Gather the crumbly dough into a ball and knead, dusting the work surface and dough lightly with flour as necessary, until it comes together into a smooth ball. Shape the dough into a rectangle, then cut into 4 equal portions; flatten each piece of dough into a 1/2-inch-thick rectangle. Wrap each section of dough in plastic wrap and refrigerate for at least 1 hour or up to 3 days.
• Make the filling: Place the chocolate in a medium microwave-safe bowl. Melt in the microwave in 30-second intervals, stirring in between, until almost melted. Stir, allowing the residual heat in the bowl to melt the chocolate completely. (Alternatively, melt the chocolates in a double boiler on the stovetop.) Mix in the sugar, cinnamon, and salt. The mixture will be grainy; that's okay.
• Line a baking sheet with parchment paper.
• Roll the cookies: Remove one section of dough from the refrigerator, unwrap it, and place it on a lightly floured work surface. (If necessary, let it sit at room temperature for a few minutes until it's pliable enough to roll, but not too soft.) Dust the top of the dough lightly with flour, then use a rolling pin to roll it into an 8 x 11-in rectangle. Don't make yourself crazy over it, but try to make it as even as possible around the edges; it will make it easier to roll. (Go ahead and trim slightly with a pizza cutter or sharp knife if it's very uneven.) Using an offset spatula or back of a spoon, quickly spread 1/4 of the chocolate filling (a heaping 1/4 cup) evenly over the dough, leaving a 1/4-inch border around the edges.
• Starting from the long side, roll the dough tightly into a cylinder. Place the filled rolled dough, seam side down, on the prepared baking sheet. Repeat with the remaining dough and chocolate filling. Place the rolled dough logs in the refrigerator for 20 to 30 minutes, or until firm to the touch.
• Preheat the oven to 375°F.
• Take the rolled dough out of the refrigerator. Using a serrated knife, slice off the uneven ends of each roll and discard. Then slice the rolls into 1-in-wide pieces. Place each slice, seam side down, on the prepared sheet. Bake for 18 to 20 minutes, or until lightly golden. Cool the rugelach on the baking sheet for a few minutes, then transfer to a rack to cool completely. Rugelach are best enjoyed fresh on the day they are baked but any extra cookies can be stored in airtight container for up to 3 days, or frozen for longer storage.
• Make-Ahead Instructions: The unbaked sliced rugelach can be chilled and stored for up to 3 days in the refrigerator before baking.
• Place the rugelach on a parchment paper-lined baking sheet and refrigerate it for 30 minutes. (You can also freeze the rugelach at this point for later use.)
• Bake the rugelach in a 350ºF oven for 18 to 20 minutes until golden brown. Transfer the rugelach to a cooling rack and let cool completely.
• Freezer-Friendly Instructions: The unbaked sliced rugelach can be frozen for up to 3 months. Before freezing, let the sliced rugelach set on a baking sheet in the freezer for approximately 20 minutes, then place in a sealable bag and press out as much air as possible. Bake as needed directly from the freezer. (Allow 1 to 2 minutes longer in the oven.) To freeze after baking: Let the rugelach cool completely and store in an airtight container separating layers with parchment paper or aluminum foil. Before serving, remove the cookies from the container and let them come to room temperature.

Ideas for Rugelach Fillings

• Nut filling: In a food processor, pulse 1 cup walnuts and 1 cup pecans until they break into tiny crumbs, 30 to 40 pulses. (Be careful of over-processing and making nut butter.) Combine the ground nuts in a bowl with 4 tablespoons (1/4 cup) melted butter, 1/4 cup honey, 1/4 cup granulated sugar, and 1 teaspoon vanilla extract.
• Fruit and jam filling: Warm 1/4 cup marmalade, apricot jam, or raspberry jam in the microwave until it liquefies. Stir in 1 tablespoon sugar. Set aside to cool until no longer steaming, still liquidy. Pulse 2 cups (roughly 10 ounces) dried fruit, such as apricots, cranberries, cherries, or currants, in a food processor until it breaks down into tiny pieces. To assemble, spread the jam onto the rugelach dough and then sprinkle the dried fruit on top.
• Peanut butter and chocolate filling: Warm 1/2 cup peanut butter in a microwave until it liquefies but isn't boiling. Spread over the rugelach dough; sprinkle with 1 cup miniature chocolate chips.