Ermine Buttercream (Boiled Milk or Cooked Flour Frosting)
Ermine Buttercream is a pudding based buttercream. Some call it boiled milk frosting, cooked flour frosting, German buttercream - you name it. I go with Ermine.
The process somewhat reminds me of the way we prepare crème pâtissière. First we need to cook the flour. Mix the dry ingredients in a saucepan and cook on low for 1-2 minutes. Make sure to mix it thoroughly.
We use this frosting in a lot of our cakes (Yes! We also used Ermine frosting in that glorious 4 tier piñata cake we designed for Madame X this year) as it tastes very light and less sweet than other buttercream recipes. It also does not have a grainy texture as we already cook the sugar with the milk which helps it dissolve.
Making the pudding
Once the flour mixture is cooked, add in the milk slowly and turn the heat up to medium. Make sure you keep whisking until the mixture thickens and bubbles up. A long French type which is very useful in this process as it can reach the corners of the pan where the flour tends to cook which causes discoloring. I have experienced that once or twice :) Once you see it bubble, turn the heat to low quickly and keep whisking for a further 1-2 minutes.
Tranfer the mixture into a bowl to cool to room temperature (or a flat surface like a baking tray if you need it to cool faster.) and cover it with cling film. Make sure the film touches the surface of the mixture so skin does not form.
Tip: If skin forms when you mix the pudding into the buttercream you will have lumpy bits which you do not want in your buttercream.
With the whisk attachment in your stand mixer, beat your room temperature butter well until it turns white. This should take about 5 minutes.
Then change to the paddle attachment and keep mixing for a further 5-10 minutes to get rid of the excess air bubbles. You can also do this stage with a hand whisk if that is what you have in hand.
This is how the consistency of the pudding should be when cooled down.
You can go ahead and start mixing your pudding into the butter. This is a good time to add in your flavouring too (if I am making a vanilla based filling then I use vanilla extract but feel free to use other flavouring like lemon extract, coffee, chocolate...).
While the butter is mixing on low, slowly add in your pudding (cooked flour mixture), mixing well after each addition. You can use a table spoon for this process as the cooled mixture is quite runny. The spatula will not hold it well.
Remember! You reduce the risk of your buttercream separating when you take it slow, so please don't rush this process. Mix in one spoonful of pudding at a time!
Once you have the consistency you are looking for, your buttercream is ready.
Storing your Ermine Buttercream
I would suggest you use it straight away but it can be stored in the fridge for a week or frozen for if you need to keep it for a longer period of time.
45g plain flour
200 g granulated sugar
1/4 tsp salt
260g full fat milk (you can also use half milk and half heavy whipping cream)
225g unsalted butter (room temperature)
1 tsp vanilla extract
Why do we cook the flour?
Flour is a raw ingredient which means it has not been treated against bacteria or harmful macroorganisms like E.coli which may cause food poisoning.
It is always unsafe to eat raw flour or use in recipes uncooked if they are not going to be cooked / baked after. Bacteria can be killed with heat (frying, baking..) that is why we need to cook the flour. Alternative to cooking on the pan, you can also bake your flour in the oven for about 5 minutes at 170C / 350F.