How much butter you need is debatable. And old French recipe book that somebody suggested to me as “the real thing” recommends 400g of butter for 500g of flour. And an old Gordon Ramsay book —“just desserts”— says 250g is enough, which is about half the amount flour.
60% butter 40% Eggs 20% Milk
400g flour 240g butter 160g eggs (about three eggs) 80 milk
You can also add
100g chocolate chips 50g sugar
to make it sweeter.