Lemon & Blueberry White Chocolate Ganache Slice
This Lemon & Blueberry White Chocolate Slice is what happens when buttery shortbread, silky white chocolate, fresh lemon, and juicy blueberries all get along perfectly.
It’s rich but balanced. Sweet but fresh. Creamy with just enough zing. And the blueberry swirl on top? That’s not just for looks… it cuts through the sweetness and makes every bite better.
This is the kind of slice you make for a gathering… and then secretly hope there’s leftovers.
Why You’ll Love This Lemon Blueberry Slice
- Silky white chocolate lemon ganache
- Buttery shortbread base
- Tangy blueberry swirl
- Make ahead friendly
- Looks impressive with minimal effort
It’s giving bakery window energy without bakery-level stress.
The Layers
1. The Shortbread Base
Buttery. Soft. Slightly crumbly. The icing sugar keeps it tender, the melted butter makes it easy to mix, and baking it until just lightly golden gives you that perfect base to hold the creamy filling. Let it cool completely before adding the ganache, patience matters here.
2. White Chocolate Lemon Ganache
This is where the magic happens. Heating the cream and pouring it over white chocolate creates that smooth, glossy ganache. Adding lemon zest brings brightness, while the lemon juice cuts through the sweetness so it doesn’t taste heavy. White chocolate can be sweet the lemon is what makes this slice feel balanced, not sickly.
3. The Blueberry Swirl
The blueberries cook down into a thick, jammy compote. The sugar enhances the berries.
The lemon juice lifts it. The cornflour thickens it just enough to swirl beautifully without bleeding everywhere. That marbled top makes it look fancy but it takes about 30 seconds…how good!
Why This Lemon Blueberry Slice Works
- Shortbread base gives structure and buttery depth.
- White chocolate ganache sets firm but creamy.
- Lemon zest + juice balances sweetness.
- Blueberry swirl adds contrast in both flavour and colour.
- Long chill time ensures clean slices.
How to Store Lemon Blueberry Slice
Keep stored in an airtight container in the fridge. It will stay fresh for up to 4–5 days… if it lasts that long. Best served slightly chilled for clean cuts but leave out for 5 minutes before serving if you want it extra creamy.
A Few Little Tips
- Use good quality white chocolate, it melts smoother and sets better.
- Make sure your base is completely cool before pouring the filling.
- Let the blueberry mixture cool fully or it can melt into the ganache.
- For super clean slices, wipe your knife between cuts.
If you love lemon desserts that aren’t too sharp and white chocolate that isn’t overpowering, this is your slice.
Watch How I Make Lemon & Blueberry White Chocolate Ganache Slice!
Share Your Lemon & Blueberry Slice!
Made this recipe? I’d love to hear about it! Share your creation and tag @Sara_elcock on Instagram or Tiktok. #OldMateEats
Lemon & Blueberry White Chocolate Ganache Slice
Ingredients
Shortbread Base
- 1⅔ cup plain all purpose flour 200g
- ½ cup icing sugar 65g
- 175 grams melted butter
- 1 tsp vanilla essence
White Chocolate Lemon Ganache Filling
- 200 grams white chocolate (buttons, drops or chopped)
- ½ cup cream 125ml
- zest of 2 lemons
- 1-2 tbsp lemon juice depending on level of lemon flavour you want
Blueberry Swirl
- 1½ cups frozen blueberries (or fresh)
- 3 tbsp white sugar
- 1 tbsp lemon juice
- 1 tsp cornflour
Instructions
Shortbread Base
- Preheat oven to 170°C and line a 20cm square slice tin.
- Mix flour, icing sugar, melted butter, and vanilla until a soft dough forms.
- Press evenly into the lined tin.
- Bake for 18–20 minutes until lightly golden.
- Cool completely.
Blueberry Swirl
- In a saucepan, combine blueberries, sugar, and lemon juice over medium heat.
- Cook until berries release juices and start thickening.
- Stir in cornflour mixture and cook 1–2 minutes until glossy and thick.
- Cool fully before using.
White Chocolate Lemon Ganache
- Heat cream until just steaming (not boiling).
- Pour over white chocolate and let sit 1 minute.
- Stir until smooth.
- Add lemon zest and lemon juice, stirring gently to combine.
Construct the Slice
- Pour ganache over the cooled base.
- Spoon cooled blueberry compote on top.
- Swirl with a knife for that marbled finish.
- Chill for at least 6 hours, preferably overnight. Do not rush the chilling. This is where it sets properly.
Notes
If the ganache doesn’t set properly
If your slice is still soft after chilling…It may not have chilled long enough this slice really needs at least 6 hours, ideally overnight. The cream may have been too hot, which can slightly affect texture. The white chocolate ratio matters!! Make sure you used the full 200g. If it’s very soft, pop it back in the fridge longer. It will continue to firm up.If the ganache splits or looks grainy
This can happen if…The cream was too hot, The mixture was stirred too aggressively, Lemon juice was added too quickly To fix it:Gently warm the mixture and stir slowly until smooth again. Always add lemon juice after the chocolate has fully melted and combined.
If the blueberry swirl sinks
The compote needs to be fully cooled and thickened before swirling. If it’s still warm or too runny, it can bleed into the ganache instead of sitting on top.If your base is too crumbly
- Make sure the butter amount was correct.
- Press the base firmly into the tin before baking.
- Let it cool fully before adding filling…warm base = soft bottom.
If it’s too sweet
White chocolate is naturally sweet But next time I would increase lemon juice slightly, add a tiny pinch of salt to the ganache and reduce sugar in the blueberry layer.FAQs
How long does lemon and berry white chocolate ganache slice need to set?
This slice needs at least 6 hours in the fridge, but overnight is best for clean slicing and a firm set.If it feels soft in the centre, it simply needs more chill time.
Can I use fresh blueberries instead of frozen?
Yes! fresh or frozen both work. Frozen blueberries release more juice as they cook, but the final result is the same once thickened with cornflour.
Why didn’t my ganache set properly?
Common reasons:
- Not enough chilling time
- Incorrect chocolate-to-cream ratio
- Using low-quality white chocolate
- Adding lemon juice before the chocolate fully melted
Also check out my recipe notes section under the recipe method for common causes and how to save it
Can I make this slice ahead of time?
Yes! It’s actually better made the day before serving. The flavours develop and the ganache sets perfectly overnight.
Can I freeze this slice?
Yes. Slice first, then freeze in an airtight container with baking paper between layers. Thaw in the fridge before serving.
Does the lemon make the ganache split?
Not if added correctly. You should Always:
- Melt chocolate with cream first
- Then gently stir in lemon zest and juice
Adding lemon too early or too fast can cause graininess.
How should I store Lemon Blueberry Slice it?
Store in an airtight container in the fridge for up to 4–5 days. Serve slightly chilled for best texture.
Love this sweet treat? Share your creations on Instagram, or TikTok and tag me so I can see your delicious results! #OldMateEats
