Preheat oven to 180°C/160°C fan/350°Line an 8” x 8” square baking pan with baking paper.
Melt the butter in a medium saucepan (choose one large enough to hold all the ingredients as the batter will all be made in the same po.
Remove from the heat and stir in the sugar, cocoa powder, Barleycup and vanilla until it’s all melted together and the sugar starts to dissolve.
Mix in the eggs until completely combined.
Sift in the flour and gently mix by hand to combine. Be sure not to overbeat the mixture or the brownies won’t be as fudgy.
Pour the batter into the prepared tin and spread out evenly to the edges.
Bake for 25 minutes or until the edges dry out and the brownie is just set but still soft and squidgy in the centre. They will continue to firm up slightly out of the oven. Leave to cool completely in the tin then carefully lift it out and cut into squares.
Meanwhile, make the drizzle by mixing the Barleycup and vanilla into 1 teaspoon of warm water until dissolved. Add to the icing sugar and mix well. If necessary to get a drizzling consistency, add a little more water to thin, or sugar to thicken. Drizzle over the completely cooled brownies.