Ingredients 

Date-Orange Filling

• 1 cup dates (about 8 oz.), pitted, quartered
• 1 teaspoon finely grated orange zest
• 1 teaspoon ground cinnamon
• 1⁄2 teaspoon kosher salt
• 1 tablespoon unsalted butter

Bring dates, orange zest, cinnamon, salt, and 1 1/2 cups water to a boil in a small saucepan. Reduce heat and simmer, stirring often and mashing with spatula, until dates are very soft and jammy, about 5 minutes. Add butter and stir until melted. Let cool.

Cookies

• 11⁄2 teaspoons baking powder
• 3⁄4 teaspoon kosher salt
• 4 cups all-purpose flour, plus more for surface
• 1 cup (2 sticks) unsalted butter, room temperature
• 1 cup sugar
• 3 large eggs

Instructions 

Whisk baking powder, salt, and 4 cups flour in a medium bowl. Using an electric mixer on medium-high speed, beat butter and sugar in a large bowl until fluffy, about 5 minutes. Add 2 eggs one at a time, beating to combine after each and scraping down sides of bowl.

Reduce speed to low and gradually add dry ingredients; mix until dough comes together. Divide dough in half and form into two 3⁄4"-thick disks. Cover and chill at least 2 hours.

Place racks in lower and upper thirds of oven; preheat to 350°. Let 1 disk of dough sit at room temperature until softened slightly, about 30 minutes.

Roll out dough on a very lightly floured surface to about 1⁄4" thick. Cut out 3 1/2" rounds with cutter and, transfer to parchment-lined baking sheets. Gather up scraps, reroll, and cut out additional rounds.

Lightly beat remaining egg in a small bowl. Brush edge of rounds with egg, then place 1 1/2 tsp. filling in center. Fold sides up to make a triangle, pinching points gently to seal and leaving about 1" surface of filling exposed.

Brush sides of folded dough with egg. Bake cookies, rotating baking sheets halfway through, until bottoms are golden brown, 18–22 minutes. Let cool on baking sheets.