Makes 4 dozen.

1 cup (2 sticks) unsalted butter, at room temperature
1/2 cup confectioners' sugar
1 large egg yolk
1 teaspoon vanilla extract
2 1/2 cups all-purpose flour
1/2 cup raspberry jam
1/2 cup confectioners' sugar
2 teaspoons fresh lemon juice
1 teaspoon cream, milk or water

Preheat the oven to 375 degrees F. Cover cookie sheet with parchment or baking paper.

Make the dough. In a large bowl, cream the butter and sugar together with an electric mixer. Add the egg yolk and vanilla and beat until light. Add the flour, a little at a time, and mix until the dough is smooth. Divide the dough into 4 parts. On the countertop, use your palms to roll each part into a strand about 3/4 inch thick and the length of the cookie sheet. Place the strands about 2 inches apart on the paper-covered cookie sheet. With the side of your little finger, press a groove down the center of the length of each strand. Bake for 10 minutes until the cookies feel firm to the touch. Remove from the oven and spoon or pipe jam into the grooves. Return to the oven for 5 to 10 minutes or until cookies are very pale golden brown.

To make the decoration, mix the confectioners' sugar, lemon juice and cream in a small bowl to make a smooth icing. Drizzle the icing down the length of the hot cookies. While the cookies are still warm, cut them at a 45 degree angle into 1-inch lengths. Let cool on the baking sheets. When the frosting is set, transfer to an airtight tin. Store in a cool place or freeze.