Shortcrust tart stopped working I have a tart recipe that has a shortcrust base that I have done several times. On the first attempts, everything was okay with the base - the "dough" was crumbly but could be rolled and kept its shape relatively well.

Now I tried making it and the "dough" turns out very crumbly, more like dry flour than dough. Rolling is impossible, and only after a lot of compaction with my hands was I able to make something workable.

The ingredients are:


  
  300 g flour
  100 g sugar
  200 g butter, cut into small cubes
  1 beaten egg
  


The instructions are:


  
  Mix flour, sugar and butter
  Add beaten egg and stir until combined
  Flatten the dough, wrap in cling-film and place in refrigerator for 2 hours
  


The instruction imply to use a food processor, but I have been using my KitchenAid stand mixer with the flat beater. I also tried mixing by hand (with a fork as well as literally by hand), with minimal improvements.

What am I doing wrong now, and why did it work before but not anymore?
If your dough is very dry and crumbly, it needs more water.

Add a few mL to the dough when adding the beaten egg.