Heat oven to 350°F; line sheets with parchment.
Beat softened butter, cream cheese, and sugar in large bowl 3-4 minutes until light and fluffy.
Mix in egg, vanilla, and lemon zest thoroughly.
Separately whisk flour, baking powder, and salt.
Gradually mix dry into wet just until combined.
Fold in graham crumbs and white chocolate chips.
Flatten about 1 1/2 tablespoons dough in palm; center 1/2 teaspoon jam. Top with another tablespoon dough; seal completely.
Roll smooth; place 2 inches apart on sheets.
Bake 12-14 minutes until edges set and centers soft; do not overbake.
Cool on sheet 10 minutes; transfer to rack. Very soft cookies firm as they cool.