Preheat oven to 350°F and line baking sheets with parchment paper.
In a large bowl, beat together the softened butter, cream cheese, and sugar until light and fluffy, about 3-4 minutes.
Add the egg, vanilla extract, and lemon zest, mixing until well combined.
In a separate bowl, whisk together flour, baking powder, and salt.
Gradually mix the dry ingredients into the wet ingredients until just combined.
Fold in the graham cracker crumbs and white chocolate chips.
Scoop about 1 1/2 tablespoons of dough and flatten slightly in your palm. Place 1/2 teaspoon of blueberry jam in the center, then top with another tablespoon of dough and seal the edges completely.
Roll into a smooth ball and place on prepared baking sheets, spacing them 2 inches apart.
Bake for 12-14 minutes until edges are set but centers still look soft. Do not overbake!
Cool on baking sheet for 10 minutes before transferring to a wire rack. The cookies will be very soft but will firm up as they cool.