Preheat the oven to 350°F/175°C. Line a 12-cup pan with cupcake liners. This recipe makes 13-14 cupcakes.
In a medium bowl, whisk together the flour, baking powder and salt.
In a stand mixer with the paddle attachment, beat the butter and sugar together on medium-high speed for 2 minutes. It should become light and fluffy.
Add the eggs and vanilla extract, then beat again on medium speed
Add in the sour cream, beating on medium-low speed until well combined
Alternate the dry ingredients with the buttermilk, starting and ending with dry.
Fill in liners with batter until they’re ⅔ full. Bake for 20-23 minutes. A toothpick inserted will come out clean with no crumbs. Let cool completely. Your cupcakes might have split at the top, almost like a muffin – this is ok!
Make Caramel
Take a small saucepan and place it on your stove over medium heat. Add the sugar ¼ cup at a time, letting the sugar dissolve completely until you add the next ¼ cup.
Stir occasionally until the sugar has completely dissolved and turns a dark amber colour. Turn the heat off.
Add the butter in a piece at a time, be careful as it may sputter! Stir with a heatproof spatula as you add the butter. Stir in the cream, salt, and vanilla. Pour into a large jar or bowl. Let cool until it is very thick.
Make Buttercream
In your stand mixer with the paddle attachment, beat the butter and confectioners’ sugar on low speed until well combined. Turn the speed to high for 2-3 minutes until light and fluffy.
Add in the salt, vanilla extract and caramel and beat again on medium speed for 2 minutes.
If your frosting isn't as creamy as you would like, add a tablespoon of heavy cream.
Assembly
Use a large piping tip to core out each cupcake. You may need to use a knife or small spatula to dig out some of the cake in case the dip didn't go down far enough.
Use a small spoon to pour in caramel until it reaches the top of the cupcake.
Pipe your frosting on top, I used a Wilton 4B tip. I then poured the rest of the caramel into a plastic squeeze bottle and drizzle it on top of the frosting.
Notes
My recipes have been developed and tested in cups and metric grams. I highly recommend using a weighing scale and measuring out your ingredients the metric way.
I make sure that all of my ingredients are at room temperature before I start the recipe, so pull out all of the ingredients before you start baking.
Butter: I use European style butter, like Kerry Gold, in my recipes. This will make your frosting much creamier and richer.
Salt: If you don’t have kosher salt, halve the amount of salt called for in the recipe. 1 teaspoon kosher salt = ½ teaspoon fine salt.
Buttermilk: You can make your own buttermilk, for every cup of buttermilk add 1 tablespoon of lemon juice to 1 cup of milk and let sit for 5 minutes.
Sour Cream: If you don't have sour cream you can use an equal amount of full fat yogurt.
Storage: Keep in an airtight container in the fridge for up to 5 days. Let it come to room temperature before eating.
Making Ahead: You can make the cupcakes ahead of time. Bake them and then once completely cooled, wrap in plastic wrap tightly. Store in the fridge for up to 2 days or in the freezer for up to 2 months. If frozen, allow to defrost and come to room temperature before frosting the cake.