3/4Cups(79g) sifted cake flour*DIY recipe in notes
1tspbaking powder
1/4tspsalt
1/4Cup(57g) unsalted butter, room temperature
1/2Cup(100g) granulated sugar
1large egg, room temperature
2Tbsp(30g) sour cream, room temperature
1tsppure vanilla extract
1/3Cup(80ml) whole milk, room temperature
Vanilla Buttercream
1/2Cup(113g) unsalted butter, room temperature
1 1/2Cups(180g) powdered sugar
1tsppure vanilla extract
1Tbspwhole milk or heavy whipping cream, room temperature
pinch of salt, or to taste
Instructions
Make the Small Batch Vanilla Cake
Preheat the oven to 350ºF and prepare three 4-inch or one 6-inch cake pan by spraying the sides with cooking spray and fitting the bottom(s) with a wax paper or parchment paper cake circle.
In the bowl of your stand mixer (a handheld mixer works fine too!), cream together the butter and sugar on medium-high until light and fluffy, about 3 minutes. Turn the mixer to low and add the egg, mixing until just combined and scraping down the bowl and paddle as needed. Add the vanilla and sour cream, turn the mixer to high, and beat for one full minute. It may look a little curdled at this point, but don’t worry – it will become smooth cake batter by the end.
Turn the mixer to low speed and add the dry ingredients all at once. Mix until just combined, then slowly pour in the milk. Continue to mix on low speed until just combined, about 30 seconds. Scrape down the sides and bottom of the bowl and give it a few stirs with a whisk to make sure there are no lumps. The batter will be slightly thin.
Pour the batter evenly between the prepared 4-inch cake pans (or all into one 6-inch cake pan). If using 4-inch cake pans, bake for 18-22 minutes. If using a 6-inch cake pan bake for 24-28 minutes. The cake is done when it springs back to the touch and a toothpick inserted comes out clean. Cool completely before assembling and decorating.
Make the Vanilla Buttercream
With a hand mixer or paddle attachment on your stand mixer, cream the butter on medium-high until it’s creamy and light (almost white) in color. About 5 minutes.
With the mixer in the off position, add the powdered sugar, vanilla, milk, and salt. Turn the mixer to low speed and mix until fully combined and uniform, scraping down the bowl and paddle as needed, 2-3 minutes.
Assembly
Once the vanilla cake is completely cooled, frost and decorate with the vanilla buttercream. To create the mini layer cake pictured, level the cake layers to your desired height. Add a swipe of vanilla buttercream onto a cardboard cake circle and place the first cake layer on top. Fill and stack the cake with vanilla buttercream, then crumb coat the cake with vanilla buttercream. Place the crumb coated cake in the refrigerator for at least 30 minutes to let the buttercream set firm.
*DIY Cake Flour Recipe: To make your own cake flour, spoon and level one cup of all-purpose flour and remove 2 Tbsp. Add 2 Tbsp of cornstarch, then sift the flour and cornstarch mixture 4 times (don’t skip that step!). After sifting, spoon and level to re-measure the amount of cake flour you need. Make ahead tips:
The small batch vanilla cake layer(s) can be made ahead and stored at room temperature, covered tightly in plastic wrap, for up to two days. Alternatively, you can cover with plastic wrap and store in the freezer for up to two months before thawing to room temperature.
The vanilla buttercream can be made ahead and stored in an airtight container at room temperature for up to 1 day. Alternatively, you can store it in an airtight container in the refrigerator for up to two weeks. When you’re ready to use it, bring it back to room temperature and rewhip with your stand mixer to bring back to frosting consistency.