Preheat the oven to 350°F / 175°C. Line a muffin pan with 6 parchment liners.
To a medium sized mixing bowl, add the flour, baking powder, salt, sugar, and cubed butter. Use a hand mixer or a stand mixer fitted with the paddle attachment to beat the mixture together until the butter has completely combined with the dry ingredients and no lumps remain.
Add in the oil, egg white, vanilla bean paste, sour cream, and milk. Whisk the ingredients together just until a cohesive batter has formed.
Distribute the batter evenly between the six liners. Bake for 15-18 min., or until a toothpick inserted in the center of the cupcakes comes out with only a few moist crumbs.
Vanilla Bean Buttercream
In a medium sized mixing bowl, add the butter and salt. Use a hand mixer or a stand mixer fitted with the paddle attachment to beat the butter and salt together for 2 minutes, until the butter is pale and fluffy.
Slowly beat in the powdered sugar until all of it has been used.
Add in the vanilla bean paste and heavy cream and beat the mixture for an additional minute.
Once the cupcakes have completely cooled to room temperature, transfer the frosting to a piping bag and frost each cupcake. Top with sprinkles, rose petals, or enjoy them as is!
I've found that this is always much easier and takes way less time when you do it in a a stand mixer. If you're using a hand mixer, just note that this is going to take a couple of minutes, and the smaller you cube up your butter, the easier it will be.
Use a kitchen scale:
I can’t stress enough the importance of a kitchen scale for accurate baking. While other things can go wrong during the baking process, using a kitchen scale helps your recipe come out closer to how mine did and can be more helpful for troubleshooting if something goes wrong. Here is a cheaper kitchen scale (affiliate link) that was trusty and helpful when I was starting with a scale. If you can’t use a scale – please make sure that you fluff up your flour with a fork, and spoon it into your measuring cup while measuring the flour.
Substitutions:
This recipe used to use buttermilk. I know a lot of people don't have a need for a whole jug of buttermilk, especially if you're just making a small batch of vanilla cupcakes, so I switched it out for sour cream and milk. If you'd like, use 85g of buttermilk in place of the sour cream and milk - you'll get a slightly more tangy (delicious) flavor.