I have been wanting to make a thick, jam-like raspberry cake filling for quite some time, so when I was writing the recipe for this lemon raspberry layer cake I thought it was the perfect opportunity! This raspberry cake filling is so delicious, can be made with fresh or frozen raspberries, and comes together easily in just 15 minutes and thickens as it cools into the perfect consistency for filling cakes and cupcakes.
Raspberry Cake Filling Ingredients & Substitutions
The raspberry filling only uses five ingredients and comes together so easily:
- Fresh or Frozen Raspberries. If you have fresh raspberries on-hand, great. Frozen raspberries are more readily available year-round, and they work perfectly for this recipe.
- Cornstarch + Water. Mixing equal amounts of cornstarch and water together creates a thickening agent for this filling.
- Granulated Sugar. This sweetens the raspberries just enough so that you still have the perfect amount of tartness.
- Lemon Juice. A little lemon juice compliments the raspberry flavor beautifully.
How to Make Raspberry Cake Filling
This raspberry cake filling comes together so easily in about 15 minutes! You will need an additional four hours for the filling to cool and thicken, but it’s a great element to make ahead of time.
Step 1: Mix together the cornstarch and water. In a small bowl, mix together the cornstarch and water.
Step 2: Add everything into a medium saucepan. Add the raspberries, cornstarch mixture, sugar, and lemon juice into a medium saucepan set over medium heat. Stir to combine the ingredients and continue stirring frequently as the raspberries soften, mashing them up as you go.
Step 3: Bring to a boil and stir frequently. Once the raspberry mixture starts to boil, you’ll reduce the heat and continue simmering it for five minutes, stirring occasionally.
Step 4: Cool the raspberry filling to thicken. Remove the raspberry mixture from the heat and add it into a glass or metal bowl. You’ll cool it for 10-15 minutes at room temperature, then cover it and place it in the refrigerator for at least 4 hours.
Four hours is the magic amount of time to thicken it perfectly, but you can also leave it in the refrigerator for up to one week. The perfect make-ahead element!
How to Fill a Cake with Raspberry Cake Filling
This raspberry cake filling is thick, but not thick enough to support a layer cake on its own. To make it more stable, you’ll need to build a buttercream dam around the edge of each cake layer before filling in the center with the raspberry filling. Buttercream is thick enough to support the weight of cake layers in the filling and stacking process. Whipped ganache also works great as a dam if that’s what you’re using to frost the cake.
To build the dam, fill a piping bag with buttercream or whipped ganache and snip off about ½ inch opening on the end. Place the first cake layer on your turntable and pipe a ring around the edge about ¼ inch inward from the edge of the layer. Then, fill in the center with raspberry filling and smooth it down until it’s level with the top of the buttercream dam or just slightly below.
Add the next cake layer on top and repeat the process of filling and stacking until you have one cake layer left. Place that final cake layer upside down on top of the filling so that the bottom of the layer becomes the top of the cake.
This process of filling and stacking the cake with a buttercream dam makes the cake with a soft filling like this much more stable, helping to prevent the filling from oozing out or bulging.
Cake Recipes to Pair With Raspberry Filling
I love using this thick raspberry cake filling in my lemon raspberry layer cake recipe, but it also pairs well with a wide variety of cake flavors! One batch of this filling will be enough to fill any of the recipes below. You’ll want to use it in place of whatever filling is listed in the cake recipe (if there is one). Here are some of my favorite suggestions:
You can also use this recipe to fill up to 15 cupcakes (here are some cupcake recipes to try)! It doubles well in case you need more.
Thick Raspberry Cake Filling
Ingredients
- 1 1/2 Tbsp (12g) cornstarch
- 1 1/2 Tbsp (22ml) water
- 2 Cups (8oz, 228g) fresh or frozen raspberries
- 1/3 Cup (67g) granulated sugar
- 1 Tbsp lemon juice
Instructions
- In a small bowl, whisk together the cornstarch and water until combined. Add it into a medium saucepan along with the raspberries, granulated sugar, and lemon juice. Set the saucepan over medium heat and stir with a rubber spatula to combine. Cook until the mixture begins to boil, mashing down the raspberries as they soften.
- Once the mixture starts to boil, set the timer for 5 minutes while you continue stirring occasionally. Then, remove from heat and transfer to a heat proof container. It won’t seem super thick at this point, but don’t worry – it will thicken significantly as it cools. Let the raspberry filling sit at room temperature for about 20 minutes, then cover and refrigerate for at least 4 hours and up to 1 week. The longer you refrigerate, the thicker and more flavorful it will be.
- When the raspberry filling has cooled and thickened, you're ready to use it as a cake or cupcake filling! If you're using it to fill a cake, be sure to pipe a buttercream dam around the edge of your cake layer before filling in the center with this raspberry filling. This way it won't squish out from between your cake layers. This blog post has more details on the filling process.
Notes
Did you make this raspberry cake filling? I want to know what you paired it with and what you think! Let me know in the comments below and feel free to tag @sugarandsparrowco on Instagram to show me. I love to see what you create!
I doubled the batch but cut back the sugar – 2 only 2 tablespoons and it was plenty sweet.
Your corn starch slurry will stick and clump so the best thing to do is let the raspberries and water cook down first and add the slurry closer to the end.