The BEST Carrot Cake - pastrychefjeff.com

Preheat oven to 350°F and prepare 4 6" cake pans with grease and parchment on the bottom. Set aside.
In a medium bowl, whisk dry ingredients together. Set aside.
In a separate large bowl, whisk vegetable oil, light brown sugar, granulated sugar, eggs, and vanilla bean paste together. Then whisk in the sour cream to the wet mixture, followed by the grated carrots. Add the dry ingredients to the wet ingredients and mix until just combined.
Distribute evenly into pans and bake for ~35 minutes, or until a toothpick comes out mostly clean (except a few crumbs). Remove and set aside to cool for 15 minutes in the cake pans before transferring to a cooling rack to cool completely.
Use a sharp serrated knife to cut the domes off the top of each cake, and crumble the cake scraps onto a parchment-lined sheet pan. Continue baking these at 300°F for ~30 minutes, or until crunchy. Remove from oven and set aside.

Add warmed heavy whipping cream to melted white chocolate and emulsify using a rubber spatula. Let cool until spreadable / a peanut butter consistency.

In a stand mixer fitted with a paddle attachment, beat together unsalted butter and cream cheese until smooth. Add salt and powdered sugar and continue mixing (start on low speed at first). Then, add vanilla bean paste and mix, making sure to scrape down the bowl.

Take one layer of carrot cake and spread ~2 tbsp of white chocolate ganache onto it, followed by cream cheese frosting (I use 3oz of frosting). Level the frosting, add another cake layer, and repeat. On top of the top layer, skip the ganache.
After adding the top layer, crumb coat the cake and let chill in the fridge for at least 20 minutes. Then, add your outer layer of cream cheese frosting, smooth, and decorate. If at any point the frosting gets too warm/loose, simply put it in the fridge to chill to firm it up again.
Finally, take the crunchy cake crumble, and add generously along the bottom of the cake and around the top.