Preheat the oven to 190°C (375°F) and line a baking sheet with parchment paper.

Cream together the softened butter and brown sugar on high speed until light and fluffy.

Mix in the egg and vanilla extract until fully incorporated.

Gradually add the all-purpose flour and salt, mixing until a soft dough forms.

Roll the dough into 1-inch balls and place them on the prepared baking sheet, spaced about 1½ inches apart.

Press your thumb or the rounded back of a teaspoon into the center of each dough ball to create a heart-shaped indentation.

Bake the cookies for 12 to 15 minutes or until the edges turn lightly golden.

Let the cookies cool on the baking sheet for 5 minutes, then transfer to a wire rack to cool completely.

Spoon a small dollop of jam into each heart-shaped center once cooled.