Preheat oven 170C/340F (or 145C fan forced).
If your eggs aren’t at room temperature, you can add them to a bowl of hot water for a few minutes before cracking them open.
Line your baking dish with baking paper.
Mix the eggs, sugar and melted oil/fat - mix well with a whisk until the eggs aren’t visible.
Sift the dry ingredients in to the wet and mix well until there are no dry spots or lumps in the batter. Ensure you are mixing the ingredients at the bottom of the bowl too. Add mix-ins if using.
Pour the batter into the baking dish, push into corners and even out the top. You can shuffle the dish around to help.
Bake for 10 minutes, turn and bake for a final 10 minutes.
Remove from oven, let cool in the pan for 20 minutes, then transfer to the fridge to set for an hour or so, uncovered.
Brownies are easiest to cut when they are completely cool (trust me) and the knife is hot. Pour boiled water on to the knife, shake off excess water and push the knife down in to the brownies in one movement to cut. This minimises waste.
If you like your brownies with some extra chew, you can store the brownies uncovered in the fridge.
Brownies can be stored in the fridge for up to a week and also freeze perfectly. Defrost at room temp or heat up in the microwave.