Preheat the oven to 180°C fan-forced / 200°C conventional (400°F)
Line a baking dish with baking paper
In a large bowl, combine all the ingredients but only use ½ of the cheddar cheese (save ½ for the top). Mix thoroughly to ensure the cheese and herbs are evenly distributed among the spinach
Pour the spinach and feta mixture into the prepared baking dish and flatten it evenly with the back of a spoon. Sprinkle the reserved cheddar cheese evenly over the top
Bake for 50-55 minutes, rotating the dish halfway through to ensure even cooking. The top should be golden, and the filling set
Let the slice cool in the baking dish for at least 30 minutes. If needed, transfer it to a wire rack to cool further. Slice into squares and serve
