Before starting, line a baking tray with a Silpat or similar heatproof liner that will release the cooled brittle. (I've seen recipes that call for plain parchment paper or parchment coated with oil or butter, but I haven't tried these methods.)

Place the pepitas and spices in a measuring cup and set aside.

Put the sugar, water and salt in a large heavy saucepan and place over medium-high heat. Stir until dissolved, while bringing the concoction to a boil. Use a pastry brush dipped in water to carefully dissolve any sugar crystals that occur on the side of the pot.

Cook until the syrup takes on a deep amber colour. It should look like a dark caramel and have the characteristic caramel aroma. (There's a fine line between just right and burned, so this may take some practice. Fortunately, the ingredients are relatively inexpensive and the time investment short should you have to start again.)

As soon as the perfect colour has been achieved, and while still on the heat, pour in the pepitas and spice mixture (they will cool down the syrup a bit). Note, there may be some bubbling up at this point. Working quickly, stir everything together. (I learned the hard way that if you take the pot off the heat to stir in the other ingredients, the mixture will cool too quickly and the sugar can crystallize.)

Quickly pour the hot syrup and pepita mixture onto the prepared tray, moving the pot as you do so to spread it out. Use a silicone spatula to further spread the mixture while hot.

Let cool and, once hard, break into pieces of the desired size.