Preheat the oven to 350 degrees. Grease a 10 x 15-inch jelly roll pan with vegetable shortening or butter. Line the pan with parchment paper. Grease the paper.
Sprinkle a large rectangle of parchment paper or a thin kitchen towel with powdered sugar and set aside.
In a small bowl, whisk together the cake flour, cocoa powder, baking powder, and salt. Set aside.
In another small bowl, combine the buttermilk, vinegar, and vanilla extract.
In the bowl of a stand mixer fitted with the paddle attachment or using a large bowl and an electric hand mixer, beat the eggs for five minutes. Slowly add the sugar and oil, then beat until well combined. Add the buttermilk mixture and red food coloring and beat again.
Add the flour mixture to the wet ingredients in two increments and beat on low speed until well combined, about 2 minutes.
Pour the batter into the prepared pan and spread evenly to reach all edges. Bake for 11-13 minutes, or until the top of the cake springs back when touched.
Immediately turn the cake out onto the prepared parchment paper or towel and peel off the paper. Very carefully roll up the cake and paper (or towel) together, starting at the narrow end. Place the cake, seam-side down, on a cooling rack to cool to room temperature, about 45 minutes.
While you wait for the cake to cool, prepare the filling.
For the Raspberry white chocolate filling
Blend ½ cup of raspberries until smooth in a heavy duty blender or food processor. Press through a sieve to remove the seeds.
Pour the raspberry puree in a small microwave proof bowl and heat until hot but not boiling. Add the white chocolate and stir until smooth. If lumps remain, return for a few seconds to the microwave. Allow to completely cool.
In the bowl of a stand mixer fitted with a paddle attachment or using a medium-sized bowl and a hand mixer, beat the cream cheese until smooth.
Add the raspberry and white chocolate mixture, then continue to beat until the chocolate is completely incorporated into the cream cheese. Be sure to scrape the sides of the bowl at least once.
Add the butter and beat until the butter is completely incorporated, about 2 minutes. Add the powdered sugar, in intervals of half a cup at a time, along with the salt and beat until the mixture is smooth and fluffy. Start with just the 1 ½ cups, adding the additional ½ if the filling is not thick enough.
Cover and refrigerate until ready to use.
Once cake is completely cooled, unroll the cake and spread the filling over the cake from edge-to-edge, leaving about ¼” on each end. Spread the remaining cup of the fresh raspberries over the top of the filling, making sure to disperse them evenly.
Re-roll the cake without the towel. Wrap the cake in plastic wrap and refrigerate for at least an hour.
Place cake seam-side down on a serving plate of your choice. Sprinkle it with extra powdered sugar and serve!
If you’d like the ends of your roll cake to look cleaner, use a sharp knife to slice off about ½ an inch of cake off each side. Do this AFTER refrigeration to avoid the filling squeezing out.