Pre-heat oven to 350F (180C). Line a large cookie sheet with parchment paper.
In a medium bow whisk together the flour, baking powder and salt. Set aside.
In a large bowl or stand up mixer beat the butter and sugar for 3-4 minutes. Add the egg and vanilla and beat to combine, approximately 1 minute.
Add the whisked ingredients to the creamed mixture and beat on low just to combine. Move the dough to a lightly floured flat surface, form into a ball, divide into 2 parts. Roll each part into a log approximately 10 inches (25cm) long. Place each log on the prepared cookie sheet.
Make an indentation down the centre, lengthwise of each log, using either a spoon or your thumb. Fill the indentation with the jam, Nutella or even pie or fruit filling. Bake for approximately 15-20 minutes. The logs are done when the bottom of the log starts to turn a light golden. Remove from the oven, let sit 5-10 minutes. then cut with a sharp knife about ½-¾ inch (1 cm) diagonal slices. Move to a wire rack to cool completely before serving. Enjoy!
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Notes
Store the cooled cookies in an air tight container at room temperate for up to 3-5 days.They can also be frozen in a freezer safe container, for up to 2 months. Separate the layers with parchment paper.