Custard buttercream (German buttercream) is a very rich buttercream icing made with the addition of custard. You can change it up by adding different flavors or liquor. This is my basic time-tested recipe for decorating cakes and cupcakes. Makes enough buttercream for one 3 to 4 layer cake or 24 cupcakes.

LenaM

Recipe Summary

prep:
15 mins
cook:
10 mins
additional:
1 hr
total:
1 hr 25 mins
Servings:
24
Yield:
24 servings
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Ingredients

24
Original recipe yields 24 servings
The ingredient list now reflects the servings specified
Ingredient Checklist

Directions

Instructions Checklist
  • Beat egg with a fork in a small, heavy saucepan. Mix in sugar and milk. Heat on medium-low heat, whisking constantly, until it just starts to boil. Continue beating rapidly until mixture thickens to a thin custard consistency. Remove from heat and cool completely, about 1 hour.

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  • Beat butter in a bowl with an electric mixer until light and creamy, about 5 minutes. Add cooled custard, 1 to 2 tablespoons at a time, beating well after each addition. Beat in rum and vanilla extract. Keep beating until buttercream is very light and fluffy.

Cook's Notes:

It is important that custard is completely cooled before using or it will melt the butter. The custard can be made ahead and chilled in the fridge until needed.

This recipe contains quite a bit of butter, for ease of decorating with a pastry bag and to help the piped icing to hold its shape. If you don't intend to create elaborate decorations and just want to simply ice your cake, you can decrease the butter to 1 cup.

If you are using the buttercream to decorate a cake or cupcakes, make sure baked goods are cooled completely to prevent the buttercream from melting. For best results when using a pastry bag, chill the buttercream in bag in the fridge for 1 hour. Chilled buttercream creates better defined shapes when used for cake decorating.

Nutrition Facts

130 calories; protein 0.5g; carbohydrates 8.6g; fat 10.5g; cholesterol 35.3mg; sodium 6.4mg. Full Nutrition
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Reviews (10)

Read More Reviews

Most helpful positive review

Rating: 5 stars
07/06/2018
This is an incredibly delicious frosting. I hate the too-sweet frostings of powdered sugar and a little butter. This is just right. It is full of butter and I enjoyed that buttery flavor and texture. If it is hot, though, it will have a tendency to break down because of the butter base. I did put sweetened coconut on the top, so that added more sugar to the final cake. The texture was delightful. If you like a light, fluffy frosting that isn't overly sweet, but full of buttery flavor, this is it. Read More
(4)

Most helpful critical review

Rating: 3 stars
12/20/2018
Did not like it. Way too much butter. Not a very good flavor. Read More
(1)
12 Ratings
  • 5 star values: 9
  • 4 star values: 2
  • 3 star values: 1
  • 2 star values: 0
  • 1 star values: 0
Rating: 4 stars
02/12/2018
Good flavor, fluffy and easy to work with. A good introduction to egg buttercream frosting: not as intimidating as Italian or Swiss buttercream but not as stable in hot, humid weather. Read More
(4)
Rating: 5 stars
07/06/2018
This is an incredibly delicious frosting. I hate the too-sweet frostings of powdered sugar and a little butter. This is just right. It is full of butter and I enjoyed that buttery flavor and texture. If it is hot, though, it will have a tendency to break down because of the butter base. I did put sweetened coconut on the top, so that added more sugar to the final cake. The texture was delightful. If you like a light, fluffy frosting that isn't overly sweet, but full of buttery flavor, this is it. Read More
(4)
Rating: 5 stars
08/01/2018
Instead of milk add buttermilk Read More
(2)
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Rating: 3 stars
12/20/2018
Did not like it. Way too much butter. Not a very good flavor. Read More
(1)
Rating: 5 stars
12/15/2018
exquisite and silky. I used this recipe as the filling in my Nanaimo bar. Custard from scratch really elevates it I'll probably never go back to custard powder. I did omit the rum flavouring and used two egg yolks in places of the whole egg for extra silkiness. Read More
Rating: 5 stars
01/26/2020
This recipe is amazing! This is my first Buttercream. The addition of the rum is a wonderful twist for the flavor Read More
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Rating: 5 stars
04/15/2020
Works very well for cupcakes - I keep them refrigerated and take out 1 hour prior to serving. For chocolate cupcakes I add 1 Tablespoon cocoa powder and substitute rum with Irish cream liquor. Read More
Rating: 5 stars
01/08/2021
I really hate extremely sweet frosting ... I was worried that it would be super sweet but it was PERFECT!! I had heavy cream on hand and used it instead of milk.... my cake was a huge hit! Everyone loved it... and I’m sure it was the buttercream!!! Yummy Thank you!! Read More
Rating: 5 stars
09/01/2019
Tastes great! Everyone loves it when I make it, even those who don't like icing will take a few bites. Read More
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