1 1/2cupsunsalted butter,cubed and at room temperature
2teaspoonspure vanilla extract
3 1/2cupsall-purpose flour
1/3cupBiscoff spread(or any cookie butter)
Cream the butter, sugar and salt in a stand-mixer on high speed until light and fluffy. Scrape down the sides, add the vanilla and then lower the speed and slowly add the flour until the dough is combined.
Roll the dough tightly in plastic wrap and flatten into a disc. Chill in the refrigerator for at least an hour or until the butter firms up. You can also use the freezer to speed up the process.
Roll out the dough to approximately one-half-inch thick. It helps to roll the dough between two sheets of parchment paper because when the butter begins to soften the dough can become sticky. Avoid using additional flour because it can dry out the cookies.
Using a two-inch cookie cutter, cut the dough into rounds and place them on a sheet tray lined with parchment paper. Roll the excess scraps into a ball and repeat the process until you have used all the dough.
To create the thumbprint, I recommend using a round one-half teaspoon measuring spoon and pressing it gently into the dough to create an even circle (you can certainly use your thumb if you prefer). Make a good-sized indentation so there's plenty of room for filling. If the cookie dough gets sticky during this process, simply place the sheet pan in the refrigerator for a bit to firm up the butter.
Chill the dough for at least 30 minutes before baking. Preheat the oven to 350 degrees F and bake the cookies for 25-30 minutes or until lightly golden on top. Allow them to cool to room temperature.
To make the filling, whisk the Biscoff spread and cream together until smooth. Place the filling in a piping bag or a plastic baggie with the corner cut off. Pipe the filling into the cookies.