If mixing in a Food Processor: Add cold butter, all-purpose (plain) or cake flour, chopped fresh rosemary and thyme, salt, egg yolk, and grated hard cheese (I used parmesan) to a food processor.
Blend in short bursts until it forms a soft dough, about 1 minute.
If mixing by Hand: In a bowl, combine flour and butter, then blend with your fingers until crumbly.
Stir in grated cheese, rosemary, thyme, and salt.
Add the egg yolk and mix until a soft dough forms.
If the dough is too dry, add cold water, 1 tablespoon at a time, until it reaches a soft consistency.
Turn out the dough on a lightly floured surface. If it’s too soft to handle, chill it in the fridge for about 10 minutes before the next step.