These raspberry thumbprint cookies are my all-time favorite cookie. Made with shortbread and raspberry jam, they are tender, buttery, and melt in your mouth.
In a large bowl, use a hand or stand mixer fitted with the paddle attachment to beat the butter on high speed until pale and creamy, about 1 minute. Add the sugar, vanilla, and almond extract, and mix on medium speed until combined. Add the flour and salt, then mix on low speed until a soft dough forms.
Line two large baking sheets with parchment paper. Roll the dough into 1-tablespoon balls and place on the baking sheet about 1 inch apart. Use your thumb to press an indentation into each ball.
Cover with plastic wrap and refrigerate for at least 3 hours until firm.
When you're ready to bake, preheat your oven to 350°F. Fill each thumbprint with about ½ teaspoon of jam.
Bake until the edges are lightly browned, about 14-15 minutes. Let the cookies cool on the baking sheet for 5 minutes before moving to a wire rack to cool completely.
Combine the powdered sugar and milk in a small bowl. Transfer to a piping bag or plastic bag with a hole cut in the corner. Pipe the filling in a zig-zag pattern onto each cookie. Allow 1 hour for the glaze to set. Enjoy!
Cookies stay fresh for about 3 days at room temperature or up to 6 days in the fridge.