Preheat the oven to 180°C. Grease and line a 22 cm square cake tin.
In a bowl, whisk together the eggs, sugar, olive oil and vanilla extract until mixed well. Add the flour, cocoa and salt and stir well to form a thick but smooth batter, then stir through the chocolate bits.
Pour the mixture into the prepared tin and bake for about 10 minutes. The centre should still be a little bit wobbly, but not liquid – poke it with your finger and if it feels set but still soft, then it’s done. Don’t over-bake!
Cool on a wire rack and cut into squares or rectangular slices to serve – the size of your slice is up to you! Serve slightly warm or leave in the fridge overnight and slice for super fudgy brownies. Brownies can be stored in the fridge for up to 7 days.