- 1 ⅔ cups (213g) all-purpose flour
- 1 cup (200g) granulated sugar
- ¼ tsp baking soda
- 1 ½ tsp baking powder
- ¼ tsp kosher salt
- ¾ cup (170g) unsalted butter, melted
- 3 egg whites, room temperature
- 1 Tbsp (15 ml) Nielsen-Massey Madagascar Bourbon Pure Vanilla Extract
- ½ cup (120 ml) sour cream, room temperature
- ½ cup (120 ml) whole milk, warm
- 5 large egg yolks
- ½ cup (100g) granulated sugar
- 3 Tbsp (45 ml) water
- 1 cup (227g) unsalted butter, room temperature and cubed
- 2 tsp (10 ml) Nielsen-Massey Madagascar Bourbon Pure Vanilla Extract
- pinch of salt
- Heat oven to 350°F. Line cupcake pans with paper liners.
- In a large bowl, sift the flour, sugar, salt, baking soda, and baking powder. Then whisk together.
- Separate the eggs. Put yolks in fridge, reserving them for the French buttercream.
- In a medium bowl, whisk together the melted butter, egg whites, vanilla extract, sour cream, and whole milk until combined. This mixture may be a little clumpy; that's a-okay.
- Pour wet mixture into dry mixture. Mix until combined, being careful to not overmix.
- Fill cupcake liners ⅔ full with batter.
- Bake for approximately 18 minutes, rotating pans halfway through the bake. Cupcakes are done when a wooden pick inserted in the centre comes out clean with only a few fluffy crumbs attached. Centres will also be springy to the touch.
- Cool cupcakes completely.
- Once the cupcakes are totally cool, make the frosting. First, in the bowl of a stand mixer fitted with whisk attachment, beat egg yolks until they are thick and foamy.
- While eggs are being whisked, combine sugar and water in a medium saucepan. While stirring, heat on low until sugar dissolves. Then increase heat to medium-high and bring mixture to a boil.
- Cook sugar mixture until it reaches 240°F (soft-ball stage). Upon reaching soft-ball stage, remove saucepan from heat immediately.
- With mixer on low, slowly pour sugar hot syrup into bowl with egg yolks.
- Keep mixing until entire bowl is cool to the touch and the yolk and sugar mixture is room temperature.
- Add butter to bowl one cube at a time, allowing each piece to be fully incorporated before adding the next cube.
- Add vanilla and salt. Keep mixing until buttercream is creamy & smooth (5–6 minutes).
NOTE: If your sugar/water mixture goes a little past soft-ball stage and you end up with a few sugar chunks in your frosting, don’t fret! After the buttercream is finished, run it through a sieve to remove any sugar chunks. Then beat with a mixer for a couple minutes.
- Pipe or spread frosting on the cooled cupcakes.
- Refrigerate the cupcakes until you’re ready to serve them.