This is a higher-octane highball. It was created at New York gastropub the Breslin, where it is served with pubby dishes like beef and Stilton pie. The orange bitters are key, says Breslin bartender Katipai Wilson, because they add "flavor without volume, and orange essence without acidity."

0.75 oz Irish whiskey
0.75 oz Amaro
2 dashes orange bitters
2 oz Guinness

Pour over ice and stir.