Taylor Swift raved about this cake! Here's our spin on it.
For the birthday crumbs:
3/4 cup all-purpose flour
1/2 teaspoon baking powder
1/2 teaspoon salt
1/2 cup white sugar
1 tablespoon brown sugar
2 tablespoons rainbow sprinkles
1/2 cup canola/vegetable oil
1 tablespoon vanilla extract
For the cake:
2 cups all-purpose flour
1 1/2 teaspoons baking powder
3/4 teaspoon salt
1/3 cup rainbow sprinkles, divided
2 teaspoons vanilla extract
1/4 cup sour cream
1/4 cup whole milk
1/3 cup canola/vegetable oil
1/2 cup unsalted butter, room temperature
1 1/4 cups white sugar
3 tablespoons brown sugar
3 large eggs
For the frosting:
6 ounces cream cheese, room temperature
2 tablespoons margarine
1 cup powdered sugar
1 teaspoon vanilla
For the soak:
1/4 cup milk
1 teaspoon vanilla
For the birthday crumbs: Preheat oven to 300 degrees, and line a baking tray with parchment paper.
In a stand mixer fitted with the paddle attachment, combine flour, baking powder, salt, sugars and rainbow sprinkles. Add oil and vanilla extract, and mix until tiny clusters of dough form. Spread clusters over prepared baking tray, and bake for 20 minutes, stirring once during baking to break up clusters. Remove from oven and allow to cool completely.
For the cake: Preheat oven to 350 degrees, and grease and line a quarter sheet pan with parchment paper.
In a mixing bowl, whisk together flour, baking powder, salt and all but 2 tablespoons of the rainbow sprinkles. Set aside.
In another bowl, whisk together vanilla, sour cream, milk and vegetable oil. Set aside.
In a stand mixer fitted with the paddle attachment, cream together butter and sugars until light and fluffy. Add eggs one at a time until well incorporated, and scrape down sides of the bowl. Continue to mix until fluffy and light. While mixing, slowly stream in sour cream mixture and continue whisking until voluminous and homogenous in texture. Slowly pour in flour mixture, and mix until just incorporated. Pour onto prepared sheet pan and spread into one even layer. Top with reserved rainbow sprinkles. Bake for 30 minutes or until a toothpick inserted in the middle of the cake comes out clean. Remove from oven and allow to cool completely.
For the frosting: Cream together cream cheese and margarine until smooth. Add vanilla and powdered sugar and continue to whisk until fully incorporated. Place in an icing bag fitted with a large round tip.
For the soak: Mix milk and vanilla in a bowl and set aside.
To assemble: Use a round cookie cutter to cut circles of cake from the sheet pan. Place the first round of cake in the base of a similarly sized Mason jar. Brush with soak mixture. Pipe in frosting, and top with birthday crumbs. With a second round of cake, pipe bottom with frosting; place frosting side down on top of birthday crumb layer. Continue layering until you reach the top of the Mason jar. Garnish with more frosting and birthday crumbs. Dig in with a spoon and enjoy!