Pre-heat oven to 325 degrees. Spray three 8-inch round or four 6-inch cake pans with nonstick spray, line the bottom of the pans with parchment paper and spray again. Set aside.

In a microwave safe bowl, microwave the white chocolate in 30 seconds increments, stirring between each 30 second increment.

In a medium sized bowl, whisk together the dry ingredients and set aside.

In a stand sized mixing bowl, beat the butter on high until light in color. Add the sugar and continue to beat until light and fluffy, about 3 more minutes.

Turn the mixer to medium-low. Add in the whole eggs and egg yolks one by one until mixed. With a rubber spatula, scrape down the sides and beat on medium high for 3 minute and then add the vanilla and the melted white chocolate. Stop the mixer and scrape down the sides of the bowl. Mix again on medium-high for another 2 minutes.

With the mixer on the lowest speed, add ⅓ of the dry ingredients followed by half of the buttermilk, then add another ⅓ of the dry ingredients, followed by the rest of the buttermilk, and then add the last part of the dry ingredients. Mix just until there are no more streaks of flour.

Pour batter into prepared pans (about 17 ounces in each 8-inch pan, and 12 ounces in 6-inch pan) and bake until slightly golden on top, 28-30 minutes. Test the cake by inserting a toothpick and look for little to no crumbs when removed.

Let the cake layers cool for about 10 minutes in the pans. Remove them from the pans and transfer them to a cake rack.

When the cake layers are room temperature, level each layer (if needed) with a cake leveler. Wrap each layer with plastic wrap and freeze or refrigerate until ready to use.

Mix sugar, water, and corn syrup in a small saucepan.

Start boiling the water and sugar mixture on medium high heat. This is the part when you do not want to stir. Let it boil until the mixture becomes caramelized and looks golden brown.

Put the cream in the microwave for 1 minute.

Turn off the heat on the sugar mixture and add the cream, being careful that it doesn’t burn you. Mix the caramel mixture until evenly combined.

Pour mixture into a bowl. Add the vanilla, salt, and butter and let it sit until the butter melts. Stir once the butter is melted.

Let it cool down to room temp.

Heat the oven to 275 degrees F. Line a baking sheet with parchment paper. Set aside.

In a medium sized bowl, whisk 1 cup of the milk powder, pretzel crumbs, corn starch, sugar and salt. Using a rubber spatula, add the melted butter and toss until the mixture starts to come together and form small clusters.

Spread the clusters on the prepped baking sheet and bake for 18 minutes. The crumbs should appear sandy at that point. Cool the crumbs completely.

If there are any bigger crumb pieces, just break them up to prevent large chunks in your cake.

Pour the melted warm white chocolate over the crumbs and toss until your clusters are covered. Then continue tossing them every five minutes until the white chocolate hardens and the clusters are no longer sticky. If not using right away, store in an airtight container and place in the fridge.

In a microwave safe bowl, heat the cream and the pour it over the white chocolate to melt. Stir until the mixture is smooth and silky. This helps prevent chunks. If there are still small chunks, heat it up in the microwave in 15 seconds increments until smooth. Don’t worry if it looks thick.

In a stand mixer fitted with a paddle attachment, cream the butter on medium-high speed for about two minutes.

Turn the mixer to low and gradually add the sifted powdered sugar until incorporated. Scrape down the sides of the bowl and continue to mix for another minute.

Add the white chocolate ganache, followed by the vanilla extract, and salt. Increase the speed to medium-high and beat the frosting for about 3 to 5 minutes, until light in color and texture.

With a rubber spatula beat out the air pockets to ensure a smooth buttercream.

Place the first cake layer, top side up, on a cake board and evenly spread about ¾ cup of the buttercream over the cake. Sprinkle about ½ cup of the pretzel filling over the frosting and press down lightly with your fingers to create a level surface. Drizzle a generous amount of caramel sauce.

Repeat these steps with the second cake layer. Place the final cake layer top-side down.
Apply a thin coat of frosting around the cake to lock in the crumbs and chill for 10 minutes in the freezer to set.

Finish frosting the cake with the remaining buttercream and top with remaining pretzel filling. Serve the extra caramel on the side. Serve room temperature.