½ cup buttermilk, room temperature (or add ½ tablespoon vinegar to half a cup of milk and stir & then let it sit for 5-8 minutes before using)
For the strawberry filling
6-8 large strawberries, washed and diced (to equal 1 cup diced)
1 tablespoon strawberry jam
For the strawberry ermine frosting
4 ½ tablespoons (35g) all-purpose flour
1 cup (200g) sugar
¼ teaspoon salt
1 cup (250ml) milk
1 cup (226g) unsalted butter, at room temperature
1 teaspoon vanilla
1 tablespoon strawberry jam
Instructions
Make the cupcakes
Preheat oven to 350°F / 175°C.
Line a cupcake pan with cupcake liners. Set aside.
Whisk together the flour, baking powder, and salt. Set aside.
In a large bowl, beat the butter and sugar until the mixture is creamy.
Add the egg and the vanilla and mix well.
Add the buttermilk and oil and mix until everything is fully combined.
Then add the flour mixture and mix until JUST combined. Don't overmix it.
Fill the cupcake liners with the batter, a little over halfway full. (I like using a ¼ cup measuring cup.)
Bake for 18-20 minutes, or until a toothpick inserted in the center comes out clean.
When the cupcakes are done, take them out of the oven and let them cool in the pan for about 5 minutes before removing them to a wire rack to cool completely.
Make the strawberry ermine frosting
In a medium saucepan, whisk together the flour, sugar, milk and salt.
Heat the mixture over medium heat and whisk continuously until it thickens, about 3-5 minutes.
When you start to see bubbles on the top, keep cooking for 1-2 minutes more, whisking continuously.
Take the saucepan off the heat and pour the mixture into a small bowl or a large sheet pan (to cool faster). Immediately cover the pudding mixture with some plastic wrap, touching the surface so that a crust won't form on the top.
After the pudding base has cooled completely, beat the butter for about 7-8 minutes.
Take a tablespoon of the cooled pudding base and add it to the butter. Beat it really well so that everything is incorporated.
Repeat, adding some pudding base, ONE tablespoon at a time, until it’s all incorporated into the butter.
Add the vanilla extract and the strawberry jam and beat 1-2 minutes more. Set aside.
Make the strawberry filling & fill the cupcakes
Wash and dice the strawberries. Put them in a sieve for a few minutes to remove excess liquid.
Put the diced strawberries in a small bowl and stir in the jam.
Using the back of a balloon whisk, gently press into the cupcakes to make a hole (don't press too hard, or it'll go all the way to the bottom of the cupcake). Or use your thumb to make a hole (see the photos in the post).
Fill each cupcake with about a teaspoon of the strawberry filling.
Then frost each cupcake using a pastry bag and tip (I use a Wilton 1M tip). Or just use a knife to spread the frosting on the cupcakes.
Enjoy!
Notes
Picture Tutorial & Tips: I have a detailed picture tutorial in my post to help you out with each step of the recipe as well as lots of tips to ensure success.
Ermine frosting is best eaten immediately after you make it. I found that it doesn't have the same texture the next day.
Frosted cupcakes can be stored in an airtight container in the refrigerator for up to about 3 days.
For accuracy, I suggest using a digital scale to weigh the ingredients before you start.
Make sure the ingredients are at room temperature. I usually leave them out for about an hour or so before starting.
Don't overmix the batter because this will make the cupcakes dense and flat.
Try not to overfill the cupcake liners or the batter overflow and make an ugly mess in the oven! That's why I use a ¼ measuring cup to fill them a little over halfway full.
Overbaking the cupcakes can make them dry. Every oven is different, so keep an eye on them so that they don't overbake.
If you store these cupcakes with the frosting in the refrigerator, make sure you take them out about 1-2 hours before serving. The frosting is PERFECT when it’s at room temperature.