Preheat your oven to 350°F (175°C) and line baking sheets with parchment paper.
In a large bowl, beat together the softened butter and powdered sugar until light and fluffy.
Beat in the egg and vanilla extract until well combined.
In a separate bowl, whisk together the flour, baking powder, and salt.
Gradually add the dry ingredients to the wet ingredients, mixing until just combined. Don’t overmix.
Shape the cookies: Roll the dough into 1-inch balls and place them on the baking sheets. You can gently press flat with your fingers or the bottom of a glass.
After forming the dough into balls, use your thumb or the back of a small spoon to make a slight indentation in the centre of each cookie. Be careful not to make the hole too deep or wide.
Bake for 15-20 minutes at 350°F (175°C), or until the edges are very lightly golden brown.
Once the cookies have cooled completely, fill the indentations with a small amount of your chosen jam. Use a teaspoon or a small piping bag for precision.
Cool and dust (optional): Let the cookies cool on the baking sheets for a few minutes before transferring them to a wire rack to cool completely. If desired, dust with powdered sugar.