pasta frolla is the basic italian short crust dough. and is used primarily for cookies (biscotti) and crostata type pies and cakes (torta della nonna or the more tuscan version, for example). the basic formula is as follows:
5 parts flour "00" or all purpose
3 parts butter
2 parts sugar
1 part egg yolks (also whole eggs but yolks or more yolks are preferred)
this is the basic formula from which you can choose to play. for instance cut 50% of the basic flour with corn flour(polenta), or whole wheat flour, buckwheat flour etc. Or with 20% cocoa powder for a chocolate crust. instead of white sugar use brown sugar (more crunch), powdered suger (more dense).
first, mix butter with sugar. best to cut sugar in with a dough cutter or use a mixer. try not to let the butter get to warm. i prefer to work with cold butter even if at first it is more difficult. you run less of a risk of the better getting hot and the water seperating from the butter.
second, mix in the egg. again with the cutter. if using a stand mixer simply add yolks at this point.
third, add flour. again use the cutter if possible. if using the mixer, careful to not over mix. work only until the ingredients combine not more.
best if left to rest 24 hours in the fridge. if in rush let rest, until cool throughout, if possible.
important points- the method aims to try to incorporate all the ingredients evenly without developing gluten. gluten is the protein network that develops when flour is contact with water and is worked. developing an elastic texture. important for pasta, crucial for leavened breads. but not for this type of pie crust or cookie dough which should be crumbly. there are two sources of water in this recipe: butter, which is around 15% to 20% water, if the butter becomes to warm, the water will separate from the butter emulsion, and the yolks/eggs. yolks are preferred because they contain more fat, less water, and their proteins coagulate less firmly. for this reason the butter should not become to hot. and the flour should be worked as minimally as possible.