I was teaching another macaron making class at my apartment last week, and the shell flavor that we made was flavored with rhubarb bitters. I filled them with rhubarb white chocolate ganache, since the previous class I had made a rhubarb jam buttercream and one of the participants said it didn't really do it for her (which is fine, since taste is so subjective, right?). So this time rhubarb jam mixed into a white chocolate ganache seemed to be a hit with my new group, who happily gobbled them up. I had a lot of leftover rhubarb jam after the class, and since I'm a big fan of jam cookies, I thought I should dust off the ol' thumbprint classic by adding some ground almond flour and giving it a kiss of lemon and rhubarb goodness. I was not disappointed in the results, and I don't think you will be either.
1 cup all purpose flour
1/2 teaspoon baking powder
1/2 teaspoon kosher salt
1/2 cup (1 stick) unsalted butter, room temperature
1/3 cup granulated sugar
1/2 cup finely ground almond flour/meal (about 2 ounces, I prefer using blanched almond flour)
1 teaspoon vanilla extract
zest from 1 regular lemon
1/2 cup rhubarb jam (recipe from Pomona Pectin's website, but I cut their recipe in 1/2 as I only had 2 cups of cooked rhubarb )
Preheat to 325°F. Line 2 half-sheet pans with parchment paper. Whisk all-purpose flour, baking powder, and salt in medium bowl to blend. Cream butter and sugar in the bowl of a stand mixer until smooth. Beat in 1/2 cup finely ground almond meal, lemon zest and the vanilla. Mix in flour mixture until just combined.
Shape large tablespoonfuls of the dough into round balls (or if you're a perfectionist like me, weigh 0.75 oz of dough to ensure identically-sized cookies). Place the rounds on your baking sheet, spacing 2 inches apart. Using your mega-sized thumb, poke a deep hole in each dough ball (or if you have a small mortar & pestle like me, you can use the skinnier end of the pestle to poke the hole). If the edges of the cookie come apart, press them back together as much as possible so your filling won’t leak out of the center. Fill each indentation with 1 rounded teaspoon of rhubarb jam. Bake cookies until light golden brown around edges, about 15-18 minutes, switching the pans front to back and top to bottom so both sheets of cookies bake evenly. Cool on baking sheet before removing. Sift powdered sugar lightly over the tops of the cookies. Makes about 20 thumbprint cookies.