Preheat your oven to 350°F (175°C) and line a baking sheet with parchment paper.
In a mixing bowl, cream together the softened butter and granulated sugar with an electric mixer until light and fluffy.
Add the egg, vanilla extract, lemon zest, and lemon juice to the butter mixture, and mix until well combined.
In another bowl, whisk together the flour, salt, and baking powder. Slowly add the dry ingredients to the wet ingredients, mixing until just combined.
Take half of the cookie dough and place it on a lightly floured surface. Roll it out to about ¼ inch thickness.
Gently spread the raspberry jam over the rolled-out dough.
Roll the dough into a log, being careful not to let the raspberry jam spill out. Wrap the log in plastic wrap and chill in the fridge for at least 15 minutes.
Once chilled, remove from the fridge and slice the log into ½-inch thick cookies, placing them on the prepared baking sheet.
Bake in the preheated oven for about 10-12 minutes or until the edges are slightly golden.
Allow the cookies to cool on the baking sheet for 5 minutes before transferring them to a cooling rack to cool completely.