Whether you wanna use it as a cake filling, pie filling, or as an ice cream topper, this simple, easy recipe for blackberry filling is a great way to make many different desserts. And, it takes no more than five minutes to prepare with fresh or frozen blackberries.

Table of Content
When blackberries are in season, you must make blackberry-inspired desserts. Right? Well, we do have them in the season, but more expensive than I would like. However, that does not stop me from making seasonal desserts. I still use some frozen blackberries with the fresh ones when necessary. For example, if I'm making a blackberry tart, I use frozen blackberries for the filling, and fresh blackberries for top and garnish.
About this filling
- A fruit filling is one that is always in my freezer. Mostly in tiny little bags. Just enough to top on small desserts or pancakes for the kids' breakfast. So, when I have a cake order that includes a fruit filling, you can bet that I will make at least twice the amount needed.
- If you noticed, I have left my fruit-filling chunky. I even take extra care when making the filling. That is why I shake the pan, not stir the fruit, so it holds its shape, though it's soft and ready to burst into tiny pieces.
- The texture is a personal preference. It depends on how you are going to use it. For example, if I were using it between cake layers, I would strain it because no one likes biting into seeds when eating. And yet, if I use it over desserts, like cheesecake, or over pancakes, then I'm not straining it. Love the chunky fruity topping.

Ingredients and substitutes
- Fresh or frozen fruits - You can definitely use either of these. Fresh berries aren't always available for me. So, frozen is often my best option. I prefer to use frozen as the fruit really breaks down nicely giving you that melt-in-the-mouth texture and mouthfeel. If you notice, unlike most other recipes that call for mashing the fruit up, I prefer to leave them whole, so they look like a berry in the desert. That mouth full of fruit when you bite into a dessert is decadent on its own.
- Cornstarch - I think this is by far the most commonly used and preferred ingredient. But if for some reason you cannot use cornstarch, try arrowroot powder or potato starch. I have used both on two different occasions - not much different.
- Sugar - I prefer to use a fine grain sugar for this, so I get a nice thick syrup consistency. If the berries are sweet, I use less than the amount of sugar mentioned in the recipe. If the berries are not as sweet, you may need to add more. The sweetness here depends on the quality of the berries.
- Lemon Juice - Helps cut the sweetness and brings out the flavor so much more.

Step by step instructions
- In a saucepan, over medium heat, add the blackberries, sugar, lemon juice, and ¼ cup water. Cook on low to medium heat until all the sugar has dissolved. Use a vegetable masher to mash some of the fruit.
Pro tip - Mashing will add a nice thicker consistency to the topping but make sure to leave some blackberries whole. - Combine the remaining water with cornstarch. Add it to the blackberries. Continue to cook on low heat until the filling is thick and glossy. Remove and let cool for a while.
Pro tip - Cornstarch can settle to the bottom of the water. So, you must stir it just before adding it to the saucepan.

- At this point, you can strain the seeds by simply pouring the filling thru a sieve. Or leave it fruity and chunky just as I have here.
- Remove and pour into a mason jar. Let cool completely or use as directed in your recipe.
Pro tip - The filling will thicken as it cools so keep that in mind when you take it off the heat.


Frequently asked questions
This filling can be kept at room temperature for up to two days. And it will last in the fridge for up to 4 or 5 days. It can also be frozen for over a month. Always keep filling recipes well wrapped to prevent drying out.
All fresh fruits are considered perishable. So yes, a cake with the blackberry filling will need to be kept in the fridge.
Absolutely, I use fresh when in season. And yet, I have to use frozen during the rest of the year. Also, the frozen ones tend to be more affordable and work best for cake and pie fillings. In addition, frozen blackberries become soft and mushy, so if you want the filling to be chunky, cook it for less time once the sugar is melted. And it will be as good as fresh blackberry filling.
You will need twice (double batch) this recipe for a blackberry pie/tart. And you can use fresh or frozen blackberries. If you have fresh save some for garnish.
A filling works great on a simple vanilla cake or chocolate cake. Also, try my vanilla cream cake or simple moist chocolate cake.
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Printable Recipe
The BEST Blackberry Filling
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Ingredients
- 7 oz (200 grams) Blackberries
- ½ cup (120 ml) White Sugar
- 1 tablespoon Cornstarch
- 1 teaspoon Lemon Juice
- ½ cup (120 ml) Water (see notes below)
- ¼ teaspoon Salt
Instructions
- In a saucepan, over medium heat, add the blackberries, sugar, lemon juice, and ¼ cup water. Cook on low to medium heat until all the sugar has dissolved. Use a vegetable masher to mash some of the fruit. Pro tip - Mashing will add a nice thicker consistency to the topping but make sure to leave some blackberries whole.
- Combine the remaining water with cornstarch. Add it to the blackberries. Continue to cook on low heat until the filling is thick and glossy. Remove and let cool for a while. Pro tip - Cornstarch can settle to the bottom of the water. So, you must stir it just before adding it to the saucepan.
- At this point, you can strain the seeds by simply pouring the filling thru a sieve. Or leave it fruity and chunky just as I have here.
- Remove and pour into a mason jar. Let cool completely or use as directed in your recipe.Pro tip - The filling will thicken as it cools so keep that in mind when you take it off the heat.
Recipe Notes
- You can use fresh or frozen fruits. Make sure to check if the fruits are sweetened and adjust sweetness accordingly.
- Also, if the fruits are frozen you may need a little less water. You can omit the additional water and add only sugar, lemon juice, and salt. Once the sugar dissolves adjust water if necessary.
- Use fine-grain white sugar so it dissolves easily and does not affect the color of the filling. For example, brown sugar can give a very dull red color.
- Overcooking the fruit filling causes the cornstarch to become lumpy. If that happens just add a little water and cook to the right consistency.
- This filling will stay in the fridge for a week but can be frozen in the freezer for up to 3 months.
- This batch would be enough a
- cake filling for 2 x 8-inch cake layers,
- a tart filling for one 9-inch tart, and
- dessert servings with a 9-inch cheesecake.
- You can use this same recipe to make any other fruit filling such as blueberry, blackberry, raspberry, mango, cherry, etc.
- Doubling the recipe - If you double the amount do not double the amount of water and cornstarch. You can add ½ cup water with 1 tablespoon of cornstarch for up to 500 grams / 15 oz of fruit. Otherwise, it takes longer to reduce the water.
- The cornstarch needs to be activated for the filling to thicken up. Otherwise, it will be very syrupy with a starchy taste.
- If the filling is too thick means the water is reduced considerably, you can add a little more to bring it to consistency. Add regular water when still hot or warm water when the filling has cooled.
- When cooled, if the filling is too thick, first give it a good mix, only then add a few tablespoons of water as necessary.
- If used to fill a cake, make sure to fruit filling make so to make a frosting dam around the edges of the cake. This will prevent the filling from coming out of the sides of the cake. See my video, how to level, fill, torte a cake
Nutrition Information
The nutrition information and metric conversion are calculated automatically. I cannot guarantee its accuracy. If this data is important to you please verify with your trusted nutrition calculator. Thank you
Shelby
I followed the directions exactly with fresh blackberries and it barely thickened at all, even after cooling. It's far too runny to put in a cake.
Veena Azmanov
Shelby, it is very important that you cook until the cornstarch thickens. It may take a few minutes but it must become a shiny thick consistency. You can add more cornstarch but that only makes the filling very starchy so I find this amount is just right. You can put it back on the stovetop and thicken it some more. Thanks