Place all the ingredients in a large mixing bowl. Season with a little salt and pepper before combining thoroughly using your hands.
Shape into 8 burger patties and place on the prepared baking tray. Place the burgers in the oven to cook for 25–30 minutes or until cooked through.
To make the whipped feta, place the feta in a small bowl and mash with a fork, add the yogurt and whip with a fork or whisk until creamy. Stir through the harissa spice and season to taste with salt and pepper.