Start by taking a cocktail shaker and filling about a quarter of it with ice cubes – you can also use cracked ice, but this might water your drink down a bit, so choose whichever type of ice you feel will work best for you.
Once the cocktail shaker is loaded with ice, you can start preparing the drink. One by one, add all the ingredients to the cocktail shaker. Start with the main ingredient – whiskey – and then follow it up by pouring in the brandy, Italian sweet vermouth, and Angostura bitters.
Next, screw the lid of the cocktail shaker on securely, so the drink remains inside and does not end up splashing all over the place when you attempt to blend it. Shake vigorously for around 15 seconds, until all the ingredients have mixed together completely, and the flavours are all amalgamated.
Now, take your serving glasses, and line them up in a row. Drop 2 ice cubes in each, then hold a strainer over them one by one as you pour in the drink. Make sure you do not fill them all the way up – leave around an inch and a half of space at the top of the glass. Your scotch and Irish whiskey cocktail is now ready – serve chilled.