1. Prepare the Dough

1. Mix Dry Ingredients: In a medium bowl, whisk together the flour, baking soda, baking powder, and salt. Set aside.
2. Cream Butter and Sugars: In a large mixing bowl, beat the softened butter, granulated sugar, and brown sugar until light and fluffy.
3. Add Egg and Vanilla: Beat in the egg and vanilla extract, mixing until fully incorporated.
4. Combine: Gradually add the dry ingredients to the wet mixture, mixing just until a dough forms.

2. Prepare the Filling

1. Blend Cream Cheese and Jam: In a small bowl, mix the softened cream cheese and blueberry jam until smooth and creamy.

3. Assemble the Cookies

1. Create Layers: Scoop out about 1½ tablespoons of cookie dough and flatten it slightly. Place a small dollop of the cream cheese mixture in the center. Cover with another flattened piece of dough and seal the edges.
2. Swirl the Topping: Use a toothpick or knife to gently swirl a small amount of the remaining jam into the top of each cookie for a marbled effect.

4. Bake

1. Preheat the Oven: Preheat your oven to 350°F (175°C).
2. Bake the Cookies: Place the cookies on a parchment-lined baking sheet about 2 inches apart. Bake for 10-12 minutes, or until the edges are lightly golden.
3. Cool: Let the cookies cool on the baking sheet for 5 minutes before transferring them to a wire rack to cool completely.