Step 1

To make the dough: In the bowl of a stand mixer fitted with a paddle (or with an electric beater), combine the flour, salt, and baking powder. With the mixer running at low speed, add the pats of butter one by one until all are incorporated and the pieces are about the size of a dime. Add the sour cream and mix just until the dough comes together.

Step 2

, Turn the dough out onto a lightly floured piece of parchment. Pat it into a 4" x 12" rectangle. Fold the dough in thirds like a letter and roll over it with a rolling pin to seal and flatten slightly. Divide the dough in half, wrap in plastic, and refrigerate for at least 1 hour, or as long as overnight.

Step 3

, To make the filling: Combine the freeze-dried raspberries and confectioners’ sugar in the bowl of a food processor, pulsing until powdered. Whisk the mixture through a fine-mesh strainer to remove any seeds; set aside.

Step 4

, To shape: Sprinkle a work surface generously with granulated sugar. Place one piece of dough on it, sprinkle the top with more sugar, and roll it into a 14" x 7" rectangle. Sprinkle half of the filling mixture over the dough, patting it in gently. Roll the dough up like a scroll from both long edges; the two "logs" will meet in the center, and eventually form the cookies' distinctive elephant ear shape. Wrap tightly in plastic and freeze for at least 1 hour, or as long as overnight. Repeat with the remaining dough and filling.

Step 5

, When you're ready to bake, preheat the oven to 425°F. Line two baking sheets with parchment.

Step 6

, To cut and bake: Remove the dough from the freezer and let sit on the counter for 10 minutes. Cut each log into 1/3" slices and lay them on the prepared baking sheets, leaving 1" of space between them. Bake for 9 minutes; the edges should be just starting to color. Remove from the oven and set on a rack; set a timer for 2 minutes. When the timer goes off, carefully turn the cookies over (this brief cooling period allows the sugar to set so it stays inside the cookies). Return the cookies to the oven and bake for an additional 3 to 5 minutes, watching carefully. Remove from the oven and let cool completely before glazing.

Step 7

, To make the glaze: Combine the confectioners’ sugar, corn syrup, and 3 tablespoons raspberry purée, whisking until smooth. Add more purée as needed to achieve a consistency that’s as thick as honey; it should fall from the spoon in a thick ribbon that disappears back into the bowl after a few seconds. Dip the cooled cookies in the glaze and place on a rack over a piece of parchment to set until the glaze is dry and firm to the touch.

Step 8

, Wrap cookies airtight and store at room temperature for several days; freeze for longer storage.