Lemon & oat crumble slice


One of my favourite things about this time of year is seeing lemon trees absolutely bursting with fruit. Lemons are undoubtedly my favourite fruit to use in my baking – and one of my favourite flavours in general – so as soon as I see the trees covered in bright yellow splotches my mind beginning ticking over with things to make.

Luckily for us we were given a bag of lemons from a friend, so I’ve been able to get into some lemony baking . The result? A beautiful baked lemon and oat slice that’s out of this world delicious. Imagine a chewy oat base topped with a layer of lemony condensed milk and finished with a generous helping of crumbled oat mixture, then baked. Sounds delicious, right?

The best thing about this recipe is how easy it is to make – the same mixture is used for the base and crumble topping, so after five minutes of mixing you’re pretty much finished! The base itself needs to be baked for 15 minutes before any of the toppings are added, giving you the perfect window to get the delicious condensed milk filling ready.


Honestly, this filling is the stuff dreams are made of – I could easily eat it by the spoonful. Basically it’s just a generous amount of lemon juice and zest mixed into condensed milk, along with a couple of egg yolks to help it set nicely once baked. I found 15 minutes was the perfect amount of time to get the filling ready, including cutting, squeezing and zesting the lemons. My favourite thing? The lemons left my kitchen smelling amazing.

After less than 30 minutes in the oven the slice was ready, though it needed around an hour in the fridge to set properly before slicing. The whole time I was itching to cut into it, to check the lemon layer baked the way I imagined it would and (of course) give it a taste test.

Luckily it was worth the wait – this slice is delicious. The slight chew of the base is offset beautifully by the crunch of the crumble topping, while the tangy lemon filling brings it all together perfectly. I honestly couldn’t get enough of the stuff – I hope you like it too!



Base & topping

  • 1 ¼ cups plain flour
  • 1 ¼ cups rolled oats
  • ½ tsp baking soda
  • ½ cup golden granulated sugar
  • ½ cup light muscovado sugar
  • 170g butter, melted

Lemon filling

  • 395g sweetened condensed milk
  • 1/3 cup fresh lemon juice
  • 2 Tbsp lemon zest
  • 2 egg yolks



  1. Preheat oven to 175 degrees Celsius and line a 25x15cm pan with non-stick foil.
  2. In a large bowl whisk together flour, rolled oats and baking soda until well combined.
  3. Add golden granulated (or white) and light muscovado (or brown) sugar and stir well.
  4. Add melted butter and mix until well combined.
  5. Turn half mixture into prepared pan and press into an even base. Set remaining aside for topping.
  6. Bake for 15 minutes.

Lemon filling & topping

  1. In a medium bowl combine condensed milk, lemon juice and lemon zest. Whisk until well combined and lemon juice no longer sits separately to condensed milk.
  2. Add egg yolks and mix until well combined.
  3. Pour onto baked base, spreading evenly. Sprinkle with remaining oat mixture until well coated.
  4. Bake for 25 minutes or until lightly golden. Place on heat-proof board in fridge to cool for approx. one hour before slicing. Store in the fridge.


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  • Neens

    Hi Kirsten, this looks delicious but I have coeliac disease and can’t eat the oats, is there something I could replace the oats with for this recipe? Coconut or something? Thanks! :o)

    • Kirsten

      Hi Neens, I think coconut would be your best bet, though can’t say for certain as I haven’t tried it. Let me know how you get on! :)

  • http://www.moveloveeat.com Amanda @ MoveLoveEat

    I try not too eat many slices with sugar and butter these days but these look seriously amazing!!

    • Kirsten

      Thanks Amanda! They are particularly delicious :)

  • Camille Goodwin

    How many squares does this recipe make? Do you use a loaf pan to bake? Thanks

    • Kirsten

      Hi Camille, I use a slice pan that’s approx 25x15cm to make this (or a large lamington pan if I double it!). I generous slice it quite generously and get around 20 pieces from a single batch, but you could make the slices smaller to get more :)