Hi all, I recently cooked the No Fuss Fruit Tart from Kitchen (p177), but found that the base was far too dry and did not set. I was using the commonly available arrowroot biscuits in Australia (375g, as per the recipe), as an an equivalent to "digestive biscuits". Just wondering if the biscuit I was using was incorrect, or the 75g butter amount is incorrect. The filling was very nice, by the way!
We suspect that the arrowroot biscuits were the reason for the tart base not setting. Arrowroot biscuits tend to be dryer than digestive biscuits as they are similar to a British rich tea biscuit. Looking at the nutritional information it appears that arrowroot biscuits contain less fat than digestives (approximately 30% vs 42% for digestives) and it is the fat in the biscuits plus the butter that tends to help the biscuit base to set.
You could still use the arrowroot biscuits as a base, but will need to add some extra butter. We would guess that the butter will need to be increased by around 15g - 30g (1-2 tablespoons). Start by adding 15g extra soft butter to the mixture then scoop out a teaspoonful of the biscuit mixture and press it between your fingers. If the mixture is starting to hold together then you should be able to use it for the base, but if it still feels a little dry and crumbly add another 15g butter, process and test again.
Also, when forming the base you need to press the crumb mixture down firmly. Using the base of a glass, measuing cup, or something similar, to press the crumbs into the tart tin will help to get a firm, even base.