Cook the Books Recipes

Tan Slice – easy to bake & delicious

The finished Tan Slice

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Tan Slice (or tan square as it was known) – as well as being amazingly delicious, is a nostalgic bake for me. My mother used to make this a lot, so all I need to do is hear the words ‘tan square’ and I’m transported back to my mother’s kitchen, and our cookie jar.  Like a lot of kiwi Mums in those days, she used to bake a lot (almost daily). Perhaps that’s where my sweet tooth has come from?!

I think this is a NZ original bake, so for those of you who’ve never heard of it, just think of a meltingly soft shortbread, covered in caramel goodness, sprinkled with more of that meltingly soft crumbly shortbread. Have I got you hooked yet? You should be! Tan slice is delicious!

As I was cruising FB yesterday, an ad popped up for a new recipe from Whittakers. Whittakers is a NZ chocolate company. Their brand has an extremely loyal following in NZ, and their business practices exemplify all that kiwis like to love about a business. The fact that they make damned good chocolate helps too!

As I was having a few friends over  (we’re allowed this in our current covid ‘alert level’), and needed to bake something,  I figured the timing with the ad was serendipitous and it was to be tan slice that I would serve for afternoon tea. Besides, who can resist anything with sweetened condensed milk.  I certainly can’t.

I’m going to digress slightly here, for my American friends, who may not be as familiar with cans of sweetened condensed milk as we are downunder. These little tins are synonymous with easy and delicious baking. I don’t think I’d be alone in saying if I see a recipe uses a tin of sweetened condensed milk, then I know it’s already halfway to being a winner! Although it’s not as well known in the States, you can buy it at your local supermarket (well, at most anyway).  I made several favourites that used sweetened condensed milk whilst I lived in the States, and EVERY.SINGLE.TIME people loved it, and begged for the recipe.  Which is a little embarrasing, because most recipes using the milk are actually extremely easy.

The Whittakers recipe for Tan Slice (they changed square to slice), is a traditional one, with the addition of chopped chocolate on the top. You can’t argue with adding chocolate into a tradition can you?   They also doubled the usual size of the filling, using two tins of sweetened condensed milk.  That equals double decadence!!

Before you head away for the recipe, read on for the tips to making this the best success.

Top Tips for your Tan Slice

These numbers relate to the method in the recipe;

Step 1

Cream the butter and sugar – to have this come out with the best consistency, ensure your butter is soft (but not melted).  Some would say room temperature is best, but room temperatures can vary a lot right!  I would also beat the butter and sugar for at least 2 minutes, to ensure it gets light enough. 

When you add the flour and vanilla, the mixture will still be quite crumbly.  This is fine, you can pour this into your tin like this.

Your base mixture when finished

This is what my base mixture looks like when I tip 2/3 of it into my tin.


To help bring it together in my tin, I use the side of a smooth even glass, or something nice and flat, to compress it.  As you’ll see here, this time I used the bottom of a ramekin (all my even glasses were in the dishwasher).  Press it firmly all over until your base is smooth.  You can see ‘circle’ marks in my base, don’t worry if you have those, they’ll be covered by the filling.

Compressing the base of your tan square into the tin using a ramekin


Step 2

A sponge roll tin is a rectangular baking tin, usually around 23x33cm (9×13 inches).  I’d recommend you line it with baking paper, which will mean you can lift it out of your tin to cut when it’s cooked.  This is really important if your tin is a nonstick one (you don’t want to damage that surface).  When lining any tin with baking paper, grease the bottom of the dish slightly with butter first – this helps the baking paper stick, so it’s not moving around when you’re putting the filling in.  Secondly, cut a diagonal line in on each corner, this will allow your paper to sit better (see in the photo below).

Baking paper lined dish - tan square

Step 3

When you’re melting the filling ingredients, keep it at a low heat, and stir frequently.  Just as it says, this can catch and burn easily.

Step 4

I don’t see any need to cool the filling, as long as you’re careful when dropping the remaining 1/3 of the base over the top.  You want to crumble this over randomly.  I forgot to take a photo of this stage, but you’ll get an idea in the finished photos how it looks.

Step 6

OK – here’s where I had to CHANGE the recipe, from adding dark chocolate.  Some of you may disagree, but I had to change it to white chocolate.

There’s two good reasons for this. Firstly, Whittakers make the best white chocolate in the world. I know, I’ve tried them all! (OK, small disclaimer, I probably haven’t tried them all, but I have tried a LOT.) Whilst the rest of their chocolate flavours are good, their white chocolate really is THE.BEST on the world stage.

And, when you’re looking for a flavour to complement caramel, I really do feel that white chocolate does it best. Dark chocolate overpowers the flavour, and I for one don’t want anything getting in the way of that delicious caramel flavour.  White chocolate is a perfect accompaniment.  Trust me!








  • Reply
    Helen Auty
    March 2, 2021 at 6:21 pm

    I grew up on this and make it often. Definitely a favourite!

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