First of all, blend the butter into cubes, well cold from the fridge, together with the flour (you will obtain a crumbly mixture), then add the sugar and salt and knead until you obtain a homogeneous dough.
Wrap it in cling film and leave to rest in the fridge for at least 1 hour.
Take the dough again, roll it out with a rolling pin between 2 sheets of baking paper until you obtain a sheet of about 1 cm, then make the biscuits by cutting the sheet into squares.
Place the biscuits in the fridge for at least 20 minutes.
Cook for approximately 10-15 minutes or until golden brown in a preheated fan oven at 180°C, then leave to cool completely.
Prepare the icing: start whipping the egg white, when it is half whipped add lemon and sugar and mix delicately.
Decorate 1/3 of the biscuits with icing, also adding sprinkles, then divide the remaining icing into 2 small bowls.
Add the colorings into the other 2 bowls, mix well and decorate the other biscuits, always adding the sprinkles at the end.
The cookie bites are ready, all you have to do is let them dry for at least 1-2 hours before bringing them to the table and enjoying them.