Preheat the oven to 175 C (160 C fan). Butter the bottom and the sides of your 8" square baking tin and line it with baking paper, with plenty of overhang.
In a medium saucepan, combine the butter and 100g of sugar and heat over a medium heat, stirring slowly until the sugar has dissolved and the butter has melted completely, about 1-2 minutes. Set aside and allow to cool slightly.
In a large bowl, whisk together the eggs and the remaining 200g of sugar until light, smooth and fluffy, about 5 minutes. Pour the sugar and butter mixture into the sugar and egg mixture and whisk to combine.
In a medium bowl mix together flour, cocoa powder, baking powder and salt. Add the dry ingredients to the bowl with sugar, egg and butter mix and whisk to combine. Do not overmix, few streaks of flour remaining are just fine. Add the chocolate and cherries and fold them with spatula until they are evenly incorporated. Pour the batter into the prepared baking tin and smooth the top with spatula. You can also reserve a small handful of chopped chocolate and scatter it over the top of brownie batter.
Bake the brownies for 35- 38 minutes or until the top of the brownies is set and shiny, with few cracks in the surface. Toothpick inserted in the middle will not be clean and should have crumb on it.
Allow the brownies to cool and set in the tin for at least 1 hour or ideally, until completely cool (I always transfer mine to the fridge to set overnight). Use the overhang baking paper to lift the brownies from the tin, slice into 16 square pieces and enjoy!
You can also bake these brownies in round, 9-inch (23 cm) cake tin. If you are using larger, rectangular baking tin, the brownies will not be as thick and will require less baking time, so make sure you keep an eye on that.
If you prefer your brownies to have more cakey, rather than fudgy texture, bake them for few minutes longer (add about 5 minutes to baking time).
Allow the brownies to cool completely before cutting them into slices.
To achieve the clean cut, use a large, sharp knife and wipe it clean between each cut.
Store sliced brownies in the airtight container at room temperature for up to 4 days. You can also store them in the airtight container in the fridge for up to 6 days.
You can freeze the brownies for up to 3 months. Wrap them tightly in a double layer of plastic wrap/ clingfilm, followed by a double layer of kitchen foil. To thaw, unwrap the brownies from the packaging and let them sit at room temperature for 3-4 hours.