• Preheat the oven to 170°C (325°F). Grease two 6-inch round cake pans and line the bottoms with parchment.
• In the bowl of a stand mixer, add the cake flour, sugar, baking powder, baking soda, and salt. Mix briefly to combine. 160 g cake flour, 150 g granulated sugar, 1 ¼ tsp baking powder, ¼ tsp baking soda, ½ tsp salt
• Add the butter to the dry mixture. Beat on low-medium speed until the mixture looks like damp sand with no large butter pieces visible. 90 g unsalted butter
• In a small jug, whisk together the milk, yogurt, and oil. Pour in 3/4 of this mixture and mix on low speed for 30–45 seconds, until a thick paste forms. 80 g milk, 50 g greek yogurt, 25 g oil
• While it’s mixing, whisk the whole egg, egg white, vanilla, and almond extract into the remaining milk mixture. Slowly stream this into the batter while mixing on medium speed. Beat for 45–60 seconds, scraping down the bowl halfway, until the batter is smooth, glossy, and free of lumps. If you have one, you can use an immersion blender and give the batter a few blasts to make it extra smooth. 1 large egg, 1 large egg white, 1 tsp vanilla extract, 1/4 tsp almond extract
• Fold in the sprinkles gently with a spatula, being careful not to overmix so the colors do not bleed. 40 g rainbow jimmies
• Divide the batter evenly between the two prepared pans. Bake for 30 minutes, or until the cakes are golden and a toothpick inserted in the center comes out with a few moist crumbs.
• Let the cakes cool in the pans for 10 minutes, then turn them out onto a wire rack to cool completely before frosting.

Frosting

• Whisk the toasted milk powder into the heavy cream. Set aside.45 g heavy cream, 1 Tbsp toasted milk powder
• Place the softened butter in the bowl of a stand mixer fitted with the paddle attachment. Beat on medium speed for 2–3 minutes, until pale and creamy. 170 g unsalted butter
• Add the powdered sugar gradually, mixing on low speed until it is incorporated. Scrape down the bowl, then increase to medium speed and beat for 2 minutes until fluffy. 340 g powdered sugar
• Pour in the cream and milk powder mixture along with the vanilla and salt. Beat on medium-high speed for 3–4 minutes, until the buttercream is smooth, light, and spreadable. ¾ teaspoon vanilla extract, pinch of salt
• Whip at low speed to combine fully, then increase to high speed and beat for 5–8 minutes. The longer you beat, the fluffier the frosting will be. If the frosting seems too stiff, add a splash more cream. If it seems too soft, add a spoonful of powdered sugar.
• To assemble the cake, place one cooled cake layer on a turntable or cake stand. Spread a layer of frosting over the top, then place the second cake layer upside down on top for a smooth, flat surface.
• Spread a thin layer of frosting around the whole cake to create a crumb coat. Smooth with a bench scraper and chill the cake for about 20 minutes until the frosting has set.
• Add a thicker layer of frosting over the cake, smoothing it with a bench scraper. If you like, use a serrated bench scraper to add decorative lines or patterns around the sides.
• This batch is enough to fill and frost a 6-inch double-layer cake generously.