Gluten Free Tan Slice
Updated: Feb 15, 2021
Makes 16 slices. Take 1 hour.
After 5 tries (5 TRIES - do you know how much condensed milk that it?!) I finally have tan slice recipe I'm happy with. And I learnt a lot about gluten free baking along the way!
If you have never had a tan slice before, welcome! Tan slice is a New Zealand tray bake with a shortcake base layer, with a condensed milk caramel, then topped with crumble and (sometimes) chocolate chips. It's absolutely delicious!
Sometimes you can't switch out ingredients 1:1
Like many of my recipes, it was my Grandma who inspired this bake. I don't know how, but tan slice seemed to be one of those things she always had on the kitchen counter freshly baked (Grandma's, am I right?). So I asked her for her recipe a while back, and tried to change nothing except swapping the wheat flour to gluten flour, hoping to make a gluten free version just as good as hers. Let me tell ya, that did NOT work. For some reason the pastry didn't bake, the caramel burnt, and the crumble melted away. I swapped a few things round, added some Xanthan Gum, and tried again...same thing happened. It turns out it wasn't so much of what I was cooking, but how I was cooking it. For some reason, and please tell me if you know why, gluten baking cooks at a quicker rate than gluten free. In fact I found that for things like slice bases, cooking longer, at a slightly lower temperature works a lot better.
So I fixed the base issue by cooking it by itself, before pouring the caramel and crumble on top. Problems solved? Unfortunately not yet. The crumble was melting into the caramel, just disintegrating! So I cooked the caramel on top of the base without the crumble. Luckily, the caramel forms a thin skin layer which you can cook the crumble on. So instead of cooking all together at once like my grandma's recipe, it actually works best if cooked in three stints! And it only took me 5 goes to figure that out...
Chocolate chips or plain?
Well, that's hotly contested. I took this question to the Coeliac NZ page, the Kiwi's in London page, and my instagram to gather votes on whether a traditional tan slice has chocolate chips or not. The reason I asked this question was because Grandma's slice never had chocolate chips, but bakeries would usually sell it with chocolate chips. As it turned out, it was basically a 50/50 split vote, so I have no clear answer on that.
I N G R E D I E N T S
For the base/crumble
170 grams of softened butter
1/2 cup caster sugar
275 grams of gluten free flour
1/2 tsp xanthan gum (omit if flour mixture already contains it)
1/2 tsp baking powder
1/4 tsp salt
For the caramel
1 tin of condensed milk (397 grams)
80 grams butter
Chocolate chips (optional)
M E T H O D
Preheat the oven to 170° celsius/bake and line a square baking tin with baking paper. I use a 9x9 inch square tin.
Beat the butter and caster sugar together until combined.
Sift the flour, xanthan gum, baking powder, and salt into the butter and mix with your hands until you can form a smooth ball of dough. It will take about 5-10 minutes, but keep at it!
Once you have a smooth dough, break off a handful and leave it to the side (this will be for the crumble on top) and push the rest of the dough into the prepare tin until its even.
Gently prick the base with a fork in several places and place in oven to bake for 20 minutes.
While the base is cooking, gently melt the butter and condense milk together in a pot over a low heat.
Once the base has cooked, removed from oven and let it cool for 5 minutes, then gently pour over base.
Put the slice bake in the oven for 5-10 minutes, or until the caramel forms a thin skin on top.
Crumble up the remaining dough, and sprinkle over the caramel. Place back into the oven for 10 minutes, or until the crumble is very slightly browned.
Remove from the oven and let the slice completely cool on a rack before sprinkling chocolate chips over, and slicing into.