Combine blueberries, sugar, and lemon juice in a small saucepan.

Cook over medium heat, stirring occasionally, until the mixture thickens and reduced to half.

Remove from heat and let cool completely before using.

In a large bowl, cream together the softened butter, white sugar, and brown sugar until smooth and fluffy.

Beat in the egg and vanilla extract until fully combined.

In a separate bowl, whisk together the baking soda and salt. Gradually add this dry mixture to the wet ingredients, mixing until just combined.

Fold in the white chocolate chunks. Drop few spoonfuls of the cooled blueberry jam and swirl carefully into the dough using a knife or skewer.

Using a 2 tbsp cookie scoop, scoop the dough onto a baking sheet and place in the refrigerator for 2 hours.

Bake for 10–12 minutes, or until the edges are lightly golden. The centers will remain slightly soft.

Let the cookies cool on the baking sheet for 5 minutes before transferring to a wire rack to cool completely.