Preheat the oven to 180°C/350°F and line an 8-inch square baking tray/dish with parchment/baking paper.

Whisk together the flour, cocoa powder, baking powder, baking soda and salt and set aside.

In a large mixing bowl, beat the butter, sugar and honey until soft. Slowly add the eggs, vanilla and milk and continue to beat until smooth. Add the flour mixture and mix to just combine. Fold in the walnuts to disperse uniformly.

Spread the batter on to the prepared baking tray and bake until a toothpick inserted comes out clean, about 22-25 minutes. Remove from the oven and let cool for 10 minutes. Turn out the brownies on to a wire rack and let cool completely. Slice into 2-inch squares or as desired.

Wrap in a plastic film and store in an airtight container for up to 10 days.