Mix together the melted butter, graham cracker crumbs, and brown sugar until fully combined. Press the mixture evenly into the bottom of a light metal 8x8 baking dish. Bake 8-10 minutes until crust is golden and fragrant. Remove from oven and allow to cool.
In a microwave safe bowl, melt butter and ½ of the white chocolate chips in a microwave in 15 second bursts, stirring after each one. When chocolate has melted and mixture is smooth, remove from microwave and allow to cool.
Meanwhile in another bowl, beat eggs, sugar and vanilla extract until smooth. Mix in the cooled butter and white chocolate mixture and then add the flour and salt. Mix on low speed until just combined.
Pour the batter on top of the cooled graham cracker crust and spread evenly.
Heat the raspberry jam in the microwave for about 10-15 seconds, just enough so that it can be easily spooned and stirred. Allow to cool for a minute, and then spoon random dollops over the top of the blondie batter. Pull a butter knife through the batter in straight lines to create a swirl. Sprinkle the top with the remaining white chocolate chips.
Bake at 325 for 35-45 minutes until the top is golden and the batter is mostly set in the center when jiggled slightly. The toothpick test will not work on this recipe as the center is meant to stay somewhat gooey. Allow the finished bars to cool completely before cutting. You may refrigerate for a couple of hours to firm them up and allow for cleaner cuts.