Step 1: Preheat your oven to 350°F (175°C). Line a large baking sheet with parchment paper.
Step 2: In a large mixing bowl, cream together the softened butter, 1 cup granulated sugar, and brown sugar until light and fluffy.
Step 3: Beat in the two large eggs one at a time, ensuring each is fully incorporated before adding the next. Stir in 1 teaspoon vanilla extract.
Step 4: In a separate medium bowl, whisk together the all-purpose flour, baking soda, and salt. Gradually add the dry ingredients to the wet ingredients, mixing on low speed until just combined. Be careful not to overmix.
Step 5: For the cheesecake swirl, combine the softened cream cheese and 1/4 cup granulated sugar in a clean bowl. Beat until smooth. Mix in the egg yolk and 1 teaspoon vanilla extract until well combined.
Step 6: Gently fold the thawed and drained blueberries into the cream cheese mixture. Be gentle to avoid crushing them too much.
Step 7: Scoop generous tablespoons of cookie dough onto the prepared baking sheet, leaving about 2 inches between each cookie.
Step 8: Take a small spoonful of the blueberry cheesecake mixture and place it on top of each cookie dough mound. Using a toothpick or a small knife, gently swirl the cheesecake into the cookie dough.
Step 9: Bake for 12-15 minutes, or until the edges are lightly golden and the centers are set. The cheesecake swirl might still look slightly soft but will firm up as it cools.
Step 10: Allow the cookies to cool on the baking sheet for 5 minutes before transferring them to a wire rack to cool completely. Enjoy!