2 1/4 cups all-purpose flour
1 teaspoon baking powder
1/4 teaspoon salt
1 cup butter, room temperature
2/3 cup sugar
2 egg yolks
zest of 1 large lemon
1 tablespoon fresh lemon juice
1 teaspoon pure vanilla extract
1/2 cup blackberry jam
- Preheat oven to 350°F. Line two baking sheets line with parchement paper; Set aside.
- Combine flour, baking powder and salt in a medium bowl. Whisk to blend.
- Place butter and sugar in the large bowl of an electric mixer, and beat until light and creamy. Add egg yolks, lemon zest, lemon juice and vanilla. Beat to combine. Add the flour mixture in two parts, beating between additions, until moist clumps form. Gather dough into a ball.
- Pinch off about a tablespoon of dough and roll into a ball. Place about 2 inches apart on prepared baking sheets. Using a floured thumb, make a shallow indentation in the center of each ball. Bake at 350°F for 10 minutes.
- While the cookies bake, measure jam into a small, heatproof bowl and microwave in 10 second intervals until stirrable and smooth.
- After 10 minutes, remove half-baked cookies from oven. Working quickly, reshape the center indentations using the back of a 1/2 teaspoon measuring spoon. Dollop 1/2 teaspoon of jam into the center of each cookie. Return cookies to the oven to bake another 10 minutes, or until light golden brown.
- Remove cookies from oven and transfer to racks to cool completely.
- Dust with powdered sugar and remove the powdered sugar from the center by dipping your finger in warm water and gently trace around the center.