Blackberry Sauce with Cornstarch

Introduction

You cook blackberries with sugar, water, and cornstarch until the mixture reduces into a thick sauce that works hot over ice cream or cold like a quick jam. Because the cornstarch thickens fast, you can finish it in about 20 minutes, which makes it useful for a last-minute dessert topping or a small-batch fridge staple.

Recipe Details

• Prep Time: 5 minutes
• Cook Time: 15 minutes
• Total Time: 20 minutes
• Servings: 4

Ingredients

• 100 g (3.5 oz / 1 cup) blackberries
• 80 g (2.8 oz / ⅓ cup) white granulated sugar
• 240 ml (8.1 oz / 1 cup) water
• 20 g (0.71 oz / ⅙ cup) cornstarch

Instructions

1. Put the fruit in a saucepan.
2. Add sugar, cornstarch, and water, and mash to a pulp.
3. Simmer or boil, uncovered, to reduce moisture.
4. Serve hot over ice cream, or cold as jam.

Variations

• Replace the blackberries with raspberries for a tarter sauce with more visible seeds and a slightly looser finish.
• Use frozen blackberries instead of fresh blackberries; they release more liquid, so the sauce may need a few extra minutes uncovered to thicken.
• Swap the white granulated sugar for light brown sugar if you want a darker color and a deeper, less sharp sweetness.
• Strain the cooked sauce through a fine-mesh sieve before serving if you want a smoother texture without blackberry seeds.
• Reduce the white granulated sugar slightly if you want a more tart, fruit-forward sauce; the final texture will be a little softer.

Tips for Success

• Mash the blackberries well in step 2 so the fruit breaks down evenly and the cornstarch disperses through the liquid.
• Keep the saucepan uncovered in step 3; if you cover it, the water will not reduce properly and the sauce will stay thin.
• Stir often once the mixture starts bubbling so the sugar and cornstarch do not settle and catch on the bottom of the pan.
• Pull the sauce off the heat when it coats a spoon lightly; cornstarch thickens more as it cools.
• If you want to serve it cold as jam, chill it fully before deciding whether it needs more cooking.

Storage and Reheating

Store the cooled sauce in an airtight container or clean jar in the fridge for up to 5 days. For longer storage, freeze it in a freezer-safe container for up to 2 months, leaving a little space at the top.

Reheat on the stovetop over low heat or in the microwave in short bursts, stirring between each one. If the sauce thickens too much after chilling or freezing, stir in a small splash of water while reheating until it loosens.

FAQ

Can you use frozen blackberries instead of fresh?

You can. Add them straight to the saucepan and cook the sauce a few minutes longer to account for the extra moisture.

How thick should the sauce be before you stop cooking it?

You want it thick enough to coat a spoon but still fluid. It will set more as it cools, especially because of the cornstarch.

Can you strain out the blackberry seeds?

You can strain the sauce after cooking if you want a smoother finish. Press it through a fine-mesh sieve while it is still warm.

Can you replace the cornstarch?

You can use arrowroot starch or potato starch in place of the cornstarch for a similar thickening effect. If you use arrowroot, keep the cooking to a gentle simmer since a hard boil can weaken the texture.