Ingredients

4-5 stalks rhubarb, about 2 cups chopped
3/4 c sugar
1/2 tsp vanilla extract
1 c (2 sticks) unsalted butter, at room temperature
1/2 c + 2 T granulated sugar
1 tsp sea salt
2 large egg yolks
1 tsp vanilla extract
2 3/4 c all-purpose flour
raw or other large-grain sugar

Directions

Chop rhubarb into pieces, then pulse in a food processor until relatively fine. Combine rhubarb, sugar, and vanilla extract in a medium sauce pan and cook over medium heat, stirring constantly, for about 15 minutes or until mixture is thick and jam-like. Spoon the hot jam into a small dish and set aside to cool while you prepare the cookie dough.

Preheat oven to 350°F. In the bowl of a standing mixer or other large bowl, beat together the butter, sugar, and salt until it is light and creamy, about 5 minutes. Mix in each egg yolk, one at a time. Scrape down the bowl between each addition. Add vanilla and mix well. On low speed, add the flour a cup at a time and mix just until combined, making sure that all dry bits are mixed in.

Set up two large cookie sheets. Make balls of dough about one inch in diameter by rolling them between your palms, placing them about two inches apart on the sheets. Once all dough has been rolled, use your finger or thumb to form a deep impression in the center of each ball. Using a 1/4 teaspoon, fill each impression with the rhubarb mixture. Sprinkle raw sugar over the cookies, focusing on the jam centers. Bake for 15 minutes or until the edges of the cookies begin to turn golden-brown. Remove sheets from the oven and allow the cookies to cool, on the sheets, for 5 minutes, then transfer them to cooling racks to cool completely.

Store in an airtight container, separating the layers by waxed paper, for up to one week.