This easy mixed berry cake filling made from frozen blueberries, blackberries, and raspberries is full of fresh and natural berry flavor. It's slightly tart, making it a perfect complement to sweet cakes and buttercreams. This easy compote is made of just four ingredients--in addition to a frozen triple berry blend, we will be adding lemon juice, sugar, and either Instant Clearjel or cornstarch.
What is a Compote?
A compote is simply a fruit filling that's been cooked down slightly and thickened. It makes a perfect filling for vanilla cakes or cupcakes.
This tried-and-true bakery recipe from Amycakes Bakery whips up incredibly quickly due to my secret bakery ingredient, Instant Clearjel, but I'll also tell you how to substitute cornstarch to get very similar results.
How to Make Easy Berry Cake Filling
Because this triple berry compote uses a frozen berry blend and Instant Clearjel, it whips up incredibly quickly. The Instant Clearjel (also known as modified cornstarch) is a tasteless thickener that makes this filling glossy and smooth (whereas cornstarch alone produces a cloudy compote that can separate over time).
Instant Clearjel does not require heat to thicken, so we are going to add it after we've cooked our berries and it will thicken instantly. You can learn more about this secret bakery ingredient in my article Instant Clearjel: a Magical Bakery Ingredient.
How to Substitute Cornstarch to Make this Mixed Berry Cake Filling
Before I discovered Instant Clearjel (which is a type of cornstarch), we used regular cornstarch to make many delicious cake fillings at Amycakes Bakery, so don't worry if that's all you have on hand.
Because cornstarch requires heat to thicken, you'll want to add it to your pan with all the other ingredients (berries, lemon juice, and all the sugar). Use cornstarch in place of instant clearjel as described within the recipe.
Cook all the ingredients while stirring until the mixture comes to a boil, then continue to stir on medium-low for about 10-15 minutes until it's quite thick. It requires a little more time than my Instant Clearjel version but makes a delicious filling.
Can You Freeze this Mixed Berry Compote?
Definitely! It freezes great before you fill the cake, and you can also freeze the cake after it has been filled with this compote. Just thaw the compote or the cake overnight in the fridge the day before you want to serve it.
Can I Use Different Berries in this Berry Cake Filling?
Absolutely--I love the convenience of the frozen triple berry blend, but I've also tried it with Strawberries, Blueberries, and Raspberries (equal parts). You can use any berries, but you may wish to adjust the sweetness to taste.
Some berries may also require more thickener than others. You can also try my Strawberry Compote Cake Filling Recipe, and my Raspberry Compote featured in my Vanilla Bean Cake with Raspberry Filling Recipe.
I hope you enjoy it! Let me know your thoughts in the comment section below, or pin it for later using the image above. 🙂
Thanks for Reading. ❤️
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Easy Mixed Berry Compote Cake Filling with Frozen Berries
- 2 ½ Tablespoons Instant Clearjel or or 2 Tablespoons Cornstarch (See Note # 1 for the differences)
- 100 grams (½ cup) Sugar
Remaining Compote Ingredients
- 8 ounces (227 grams, around 2 cups) Frozen Berry Blend (unsweetened) (I use Frozen Natural Triple Berry Blend. It's a mix of blackberries, raspberries, and blueberries. You can also use 3 different types of frozen berries in equal parts.)
- 1 ½ Tablespoons Lemon Juice (I use bottled)
- Whisk the sugar and your choice of 2 ½ Tablespoons Instant Clearjel or 2 Tablespoons Cornstarch together in a small bowl. Set aside.
- Combine the frozen berries and lemon juice in a nonstick skillet or saucepan.
When using Instant Clearjel
- If you're using Instant Clearjel, cook the frozen fruit and lemon juice on medium heat until the berries are fully thawed and the liquid begins to simmer. Using a sturdy spatula, cut any large berries into very small pieces (around ¼ inch pieces) as they simmer. The berries should be soft enough that they are easy to cut with the spatula. Cook for about 5 minutes or until the berries are softened and you are happy with their size.
- Remove from heat and immediately add the Instant Clearjel/Sugar mixture and stir in quickly until it dissolves. The compote will thicken immediately, and continue to thicken as it cools. *Reminder--make sure you are using INSTANT clearjel. Cooktype and original clearjel do not work the same as Instant and require heat to thicken like the cornstarch method*
When Using Cornstarch
- If you're using Cornstarch, add the cornstarch/sugar mixture to the pan of frozen fruit and lemon juice and stir. Cook on medium heat until the berries are fully thawed and the liquid begins to simmer. Using a sturdy spatula, cut any large berries into very small pieces (around ¼ inch pieces) as they simmer. The berries should be soft enough that they are easy to cut with the spatula. Cook for about 10-15 minutes as the mixture boils, scraping the pan frequently with a sturdy spatula. The compote is finished when it is thick and coats your spatula and the berries are soft.
How to Store it
- Chill the berry compote in the refrigerator up to 2 weeks. It may be used from cold as a cake or cupcake filling (See Note #2). Enjoy!
- Read my article Instant Clearjel: a Magical Little-Known Bakery Ingredient to see why I think this ingredient is worth having in your pantry. Instant Clearjel must always be whisked thoroughly with other dry ingredients before being added to wet ingredients to avoid clumping. Cornstarch works great as well--the difference is that the Instant Clearjel option will be slightly thicker and glossier, and unused compote made with cornstarch can separate slightly the longer it sits in the fridge--simply stir before using.
- When using triple berry compote as a cake filling, pipe a 1-2" tall ring of buttercream around the edge of the cake, then spoon the compote in the middle of the buttercream ring (as shown in my Berries 'n' Cream Cake recipe). This will prevent the compote from spilling out of the cake.