Preheat the oven to 180°C / 160°C Fan / Gas Mark 4 and grease your loaf tin, lining it with baking parchment
Put the butter, dark chocolate and salt in a heatproof bowl and place over a pan of hot water, making sure the water is not touching the bottom of the bowl. Use a wooden spoon or heat-proof spatula to move the ingredients around the bowl gently until they melt and combine, then set aside to cool.
Once the chocolate mixture has cooled stir in the sugar, vanilla and the egg (don’t worry if your thawed egg has a thick, slightly gloopy consistency). Mix together until fully combined.
Add in the cornflour and ground almonds and mix thoroughly. Add the cornflour-coated halved cherries and mix again.
Pour the batter into the loaf tin and smooth down. Bake for 20-25 minutes until the brownies have risen and the internal temperature is ideally between 85 and 88°C, up to 99°C (check it with a food probe thermometer!).
Once fully cooled you can slice up and eat your brownies, or even better, pop them in the freezer, then enjoy straight from frozen with a piping hot drink!