Place the flour, baking powder, and salt into the food processor. Pulse to mix. Cut the butter into small cubes and add them to the flour. Mix until the mixture resembles streusel. Add the egg yolks, sour cream, and crumbled feta and mix to incorporate well.

Preheat the oven to 180 degrees Celsius/ 350 degrees Fahrenheit.

Divide the dough into 2 or 3 parts and keep the rest of the dough wrapped in cling film in the fridge, while you cut the first batch of pretzels or sticks.

Roll the dough about 3 or 4 mm/ 0.12 – 0.15 inches thick on a lightly floured surface. Cut with the pretzel cutter if you have one. Remove the pastry bits inside the holes of the pretzels. You will roll them again with the next batch of pastry.

If you don't want to use a cutter, cut the dough into strips, about as long and thick as a finger.

Place the pastry onto baking trays lined with baking paper. Brush them with the lightly beaten egg and sprinkle them with the seeds of your choice. For an even cheesier version, you could sprinkle some of them with some Parmesan as well.

Bake for 12-15 minutes or until nicely golden. Check the first batch repeatedly to make sure you get the baking time right, ovens are different and you don't want to overbake the pretzels.

While one batch is in the oven, cut the second batch, and so on. You should have at least 2 baking trays/ cookie sheets, it makes the baking process quicker and easier.

Leave the pretzels or sticks to cool slightly before you transfer them to wire racks to cool completely. If you try to move them immediately after baking, they might break, so better leave them on the tray for about 5 to 10 minutes or so.

They will keep for at least one week in an airtight container (probably longer, if you manage).