Prepare the Dough:

1. Whisk together flour, salt, cardamom, and cinnamon in a medium bowl; set aside. Beat cream cheese and butter with a stand mixer fitted with a paddle attachment on high speed until smooth, about 1 minute, stopping to scrape down sides of bowl as needed. Reduce mixer speed to low; add one-third flour mixture. Beat on low speed until flour mixture is incorporated, about 20 seconds. Repeat process twice with remaining flour mixture, stopping to scrape down sides of bowl as needed. Increase mixer speed to medium-high, and beat until Dough is as smooth as possible, about 1 minute. If necessary, knead Dough in bowl until it comes together.

2. Roll Dough into a thick log on a well floured surface using floured hands. Cut into 3 equal pieces. Roll each piece into a ball; flatten into a circular disk. Wrap disks separately in plastic wrap, and refrigerate at least 2 hours or up to 24 hours.

Prepare the Date And Walnut Filling:

1. Process walnuts, dates, sugar, cinnamon, cardamom, and lemon zest in a food processor until nuts and dates are finely chopped but not a paste, 20 to 30 seconds, stopping to scrape down sides of bowl as needed. Add date syrup, and process to combine, 5 to 10 seconds. Transfer to an airtight container, and refrigerate until ready to use.

Assemble the rugelach:

1. Line 3 baking sheets with parchment paper. Working in 3 batches, remove 1 pastry disk from refrigerator. Place disk on a floured surface, and sprinkle Dough with flour. Roll Dough into an 11-inch round, lifting and moving Dough as you roll to prevent sticking. (It’s fine if the round is a little rough around the edges.)

2. Brush Dough with 2 tablespoons of the date syrup. Using a dough cutter or back of a knife, cut Dough round into 12 equal triangles. Take one-third of Filling out of refrigerator. Spoon 1 tablespoon Filling onto each triangle, spreading and leaving about an 1/8-inch border at ends and edges of triangle. Starting from wide end of each triangle, roll up each piece to the point; place on prepared baking sheet, point side down. Chill rolled cookies until firm, about 30 minutes. Meanwhile, preheat oven to 350°F.

3. Lightly brush the top of each cookie with beaten egg, and sprinkle cookies evenly with 1 tablespoon of the sugar. Bake in preheated oven until tops are golden and bottoms are browned, 25 to 28 minutes, rotating baking sheet from front to back after 10 minutes of baking. Check cookie bottoms after 20 minutes of baking, and if necessary, place baking sheet on top of another baking sheet to slow browning. Carefully transfer cookies and parchment paper to a wire rack, and let cool completely, about 1 hour. Baked cookies may be stored in an airtight container at room temperature up to 2 days or frozen up to 1 month.

Prepare the Tahini Glaze:

1. Whisk together tahini, boiling water, lemon juice, and 3/4 cup of the powdered sugar in small bowl. Gradually whisk in remaining 3/4 cup sugar until glaze is very thick. (Glaze should not be runny but still thin enough to be drizzled off the tines of a fork.) Add additional boiling water or powdered sugar, 1 teaspoon at a time, as needed for desired consistency.

2. Using a fork, drizzle glaze evenly over cooled cookies. Let glaze dry at room temperature, 1 to 2 hours. Store cookies in an airtight container at room temperature for up to 2 days, separating layers with wax paper or parchment paper.