I love our rustic blueberry buttercream frosting, but the fluffy, buttery, bakery-style icing is the favorite around here. It’s a little more complicated to make, but the myth of its difficulty is more legend than truth. You’re basically going to turn fresh blueberries into juice, add hot syrup (water and sugar) to egg whites and cream of tartar, whip it all up and add some room-temperature butter. This recipe is laid out step-by-step and should be fool proof. As the resident fool of our kitchen, I’ve tested this claim extensively and have yet to ruin a batch. This comes from a man that rarely leaves the kitchen without a band aid on something, so it’s not like it even takes a lot of coordination. It’s based on our bakery-style italian vanilla buttercream. It’s scaleable from just under two cups to just around three cups by doubling everything and sticking with the directions. The smaller batch listed here comfortably covers a 2 layer, 6″ cake. I typically make the larger batch to leave room for a nice, thick and even finish, but it stores easily at room temperature for 4-5 days in an airtight container or in the freezer for a few months in an airtight ziplock bag. This is an absolutely perfect, delicate icing for our lavender cake, an Earl Grey cake that we’ve been making recently and it makes a chocolate brownie an epic experience. Try it on a vanilla cake with chocolate ganache filling between the layers…your head will explode with joy. Soooo good.
We’re listening to Mumford and Sons, Babel on vinyl in the kitchen today. If you don’t know this folk influenced rock band out of England, you want to.
Ingredients: (makes a little less than 2 Cups)
1 Cup organic granulated sugar (plus 2 Tbsp for the blueberry syrup)
1/3 Cup water (plus 2 Tbsp for the syrup)
3 Large organic egg whites, at cool room temperature
1/2 tsp. cream of tartar
1 1/2 Cups organic, unsalted butter, room temperature, split into 10-12 pieces
1 Tsp. pure organic vanilla extract
1 1/2 Cups fresh blueberries
Over medium heat in a small sauce pan, bring water and sugar to a simmer and cook until the sugar syrup reaches 250 degrees (f). Clip a candy thermometer to the side of your pan and watch the temperature closely.
While your syrup is coming to temperature, add the egg whites and cream of tartar to the mixing bowl of an electric mixer, fitted with a wire whisk attachment. When the syrup reaches 250 degrees (f), immediately move it to a heat proof container with a spout for pouring (I use a glass measuring cup as seen in the photos). Begin whipping the egg whites and cream of tartar at medium speed, then pour about 3 Tbsp of the hot syrup into the egg whites by letting it trickle down the inside of the bowl, slightly cooling the mixture before it reaches the egg whites (see bottom of this post for reference on method). As the peaks begin to form, add the remainder of the hot syrup in the same manner a few ounces at a time until it is all added. Increase mixer speed to high and continue to whip until the mixture is at room temperature, about 5-7 minutes. Feel the side of the mixing bowl to gauge.
Reduce the mixer speed to medium once the mixture is at room temperature, then add the room temperature butter, a single piece at a time, waiting to add the next until each piece is fully incorporated. Increase to high speed. The icing might look a bit curdled at first, but it comes together, so have faith and be patient. Whipping can take 10-15 minutes depending on temperature and until your frosting is fluffy, spreadable and slightly glossy. Slow your mixer to medium-low, add the vanilla and let it incorporate completely as your final step.
To make blueberry juice, add 1 1/2 cups of slightly mashed fresh blueberries to a medium saucepan, along with 2 Tbsp water and and 2 Tbsp sugar, cook on medium-low heat until blueberries are liquid. Strain through a fine mesh sieve into a clean container and let cool completely. Makes about 3/4 Cup of juice. For each cup of buttercream frosting, add 3-4 Tbsp blueberry juice and stir with a wooden spoon until thoroughly combined and uniform in color.
Adding hot syrup to the egg whites.