Cook raspberries and 1 tablespoon sugar in a medium saucepan over medium heat until soft and juices are released, about 5-7 minutes. Puree in a food processor and strain through a fine sieve to remove seeds. Set aside to cool completely.

Sift 2 cups flour, baking powder, and salt in a large bowl. Set aside.

In a stand mixer bowl fitted with a paddle attachment, cream butter and 1 cup sugar on medium speed until light and fluffy. Add egg yolks one at a time and vanilla until well blended, scraping down the bowl occasionally.

Gradually add flour mixture and beat until well blended and no longer crumbly. Remove half of the dough from the bowl and form into a small disk. Set aside.

To the remaining dough in the bowl, add 3 tablespoons of raspberry puree and the additional 5 tablespoons of flour. Beat until dough is all the same color. Form into a disk.

Roll out each disk of dough between two sheets of wax paper into roughly 14x8 rectangles and 1/8 inch thick. Slide dough onto two large baking sheets and refrigerate for about 1 hour.

Place nonpareil decors in a 9x13 pan. Set aside.

Remove dough from refrigerator. Lay rectangles side by side with the long side closer to you and carefully peel away top layer of wax paper from both doughs. Brush the top of raspberry dough lightly with water.

Place vanilla dough on top of raspberry dough, paper side up. Roll over the top of the wax paper with a rolling pin very gently to seal the dough together.

Carefully remove the top sheet of wax paper from the vanilla dough. Trim the edges of the dough to make a neat rectangle.

Beginning with the long side, roll the layers into a tight cylinder, peeling off the bottom sheet of wax paper as you roll. Press at the seam to seal and trim the ends.

Gently roll the log in the nonpareil decors until completely coated. Wrap tightly in wax paper and refrigerate for 3-4 hours or until firm enough to slice.

Preheat oven to 325 degrees. Slice the log into 1/4 inch slices and place on parchment lined baking sheets, one inch apart.

Bake one sheet at a time for 12-14 minutes, or until tops are firm and bottoms are lightly browned.

Let cool on baking sheet for 5 minutes then remove to wire racks to cool completely.