Lucky Butter Old Fashioned: A Special Edition Cocktail Breakdown

Every once in a while, a cocktail hits that perfect intersection of fun technique, decadent flavor, and actually doable at home.

The Lucky Butter Old Fashioned checks all three boxes: Irish whiskey fat-washed in brown butter, Guinness Demerara syrup, aromatic bitters, and an orange peel. It’s rich, silky, toasty, and low-key tastes like someone convinced St. Patrick to start a cocktail program.

A lot of you asked for the full breakdown, so this entry to Simple Syrup Monthly is a special-edition deep-dive into how to make the two key components:

1. Brown Butter–Fat Washed Whiskey

2. Guinness Syrup (2:1)

Let’s get into it.

Brown Butter–Fat Washed Whiskey

Fat-washing sounds "uppity," and honestly kinda weird sometimes, but it’s one of the simplest cocktail techniques out there. You’re infusing the whisky (or your spirit of choice) with the flavor of browned Irish butter, then freezing it so the fat solidifies and separates cleanly. It takes a bit of time, but overall is pretty easy to do.

What You’ll Need:

• 750 ml Irish whisky (I went with Jameson Black Barrel)

• 2–3 tablespoons browned Irish butter (I used salted Kerrygold for a richer, toastier flavor; use unsalted if you want a gentler finish)

• 1 large jar with a tight seal

• Freezer

• Coffee filter (saturated with water before using)

Instructions:

1. Brown the butter:
   Heat the butter in a small pan until golden, nutty, and aromatic. Let it cool slightly.

2. Combine:
   Add the butter to your jar, then pour in the whiskey. Seal and shake gently.

3. Infuse at room temp:
   Let it sit at room temperature for 1–2 hours, shaking occasionally. This is where most of the flavor transfer happens.

4. Freeze:
   Move the sealed jar to the freezer overnight.
   Optional trick: Flip the jar upside down. This causes the fat to freeze into a firm layer at the bottom, making it incredibly easy to pour out the whiskey the next day.

5. Strain for clarity:
   Pour the whiskey through a water-saturated coffee filter.
   (Saturating the filter prevents it from absorbing your spirit, plus the any small fat particules will "cling" to the filter.)

6. Store:
   Bottle your fat-washed whiskey and keep it in the fridge.
   Shelf life? I don't know... you'll drink it all long before it's ever an issue.

Guinness Demerara Syrup (2:1)

Guinness reduces beautifully: malty, slightly bitter, and perfect for pairing with whiskey.

What You’ll Need:

• 1 can Guinness

• Demerara sugar (twice the volume of the reduced stout)

Instructions:

1. Reduce the stout:
   Pour Guinness into a saucepan and simmer on medium heat until it reduces by half. This concentrates the flavor and removes excess water.

2. Add sugar:
   Measure the remaining liquid, then add twice that amount in Demerara sugar.
   (Example: If you have ½ cup of reduced Guinness, add 1 cup of sugar.)

3. Dissolve:
   Heat gently, stirring until the sugar fully dissolves. Once it reaches a light simmer, remove from heat and cool.

4. Bottle + store:
   Add to a resealable bottle. Store at room temperature for 1–2 weeks.

Note: For this video, my Guinness reduction was right around 125g on the kitchen scale, so I added 250g Demerara to make my 2:1 syrup.

Building the Lucky Butter Old Fashioned

Here’s the formula:

• 2 oz brown butter–fat washed Jameson Black Barrel

• ¼–½ oz Guinness Demerara syrup

• 4-5 dashes aromatic bitters (cardamom bitters would be lovely here)

• Stir with ice, strain over a big cube, express an orange peel over the glass and drop it in

It’s rich, silky, slightly malty, and absolutely nails the “Irish dessert but make it boozy” vibe.

Final Pour

This is one of those cocktails that feels like a magic trick when you hand it to someone. If you give the fat-wash and Guinness syrup a try, tag @highproofpreacher so I can see your version.

And if you’re not already subscribed, join Simple Syrup Monthly to get more deep-dive recipes like this every month.

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