The Cookie Rum Old Fashioned - Revisiting a Cocktail Time Classic!

Hi, Friends of Cocktails! It’s funny how a long journey can bring you back to the place where you started, and today that’s all the way back to 2020 when I made the Rum Old Fashioned. But today we’re taking that recipe and making it even butter… I mean better, with the Rum Old Fashioned 2.0–an Old Fashioned with all of the best parts of a chocolate chip cookie.

My original Rum Old Fashioned was a pretty straightforward cocktail, made with Diplomatico Reserva Exclusiva rum, rich demerara syrup, and homemade chocolate and coffee bitters. So in the true Artisans of Taste spirit, which is a programme championed by Diplomatico Rum, I went on a mission to elevate the simple but delicious Rum Old Fashioned.

The final recipe ended up being pretty simple, but it really took me a lot of trial-and-error to get it right. You don’t usually get to see the R&D part of the process, but I think it’s important for everyone to know that new cocktail ideas don’t always pop into your mind as a finished recipe.

My first draft was a cookie syrup made with two enzymes: amylase and glucosidase. Amylase breaks starches into dextrins and sugars, and glucosidase takes those dextrins down to glucose for sweetness and fermentability. The syrup tasted great, but with the small amount needed in an Old Fashioned it wasn’t pungent enough to turn the Old Fashioned into a true “cookie” experience. I'll cover the recipe for this on my Patreon if you want to learn more about enzymes too.

The second attempt was a cookie milk wash, like we did with the Donut Old Fashioned and Brownie Manhattan, both inspired by the video of James Hoffmann drinking donuts in coffee. The method worked great in the Donut Old Fashioned, but even then we ran into a scenario I really wanted to avoid with this one: Alongside a slight starchy note the cocktail also turned cloudy when chilled with ice.

This phenomenon, known as louching or the Ouzo effect, happens when oils which are soluble in alcohol at higher concentrations separate out when diluted. Long story short, I wanted the cocktail to look just as good as it should taste. So it was back to the drawing board… and then I realized I have to look at the cookie as the sum of its parts and start there!

Splitting the cookie into components meant I can incorporate them separately into the drink. Chocolate, butter, sweetness, vanilla, nutiness, salt, and it all came together after that. So let’s go over the ingredients that will make our improved Chocolate Cookie Rum Old Fashioned, starting with the brown buttered rum, adding body and rich buttery, nutty notes. It’s Cocktail Time! 

Brown Buttered Rum

● 400mL · 13.5oz Diplomatico Reserva Exclusiva Rum

● 40g Unsalted Butter

Just like 5 years ago, we’re again going with Diplomatico’s Reserva Exclusiva, a premium blend aged up to 12 years, known for its rich notes of toffee, vanilla, and dark chocolate. It’s smooth and luxurious, which makes it an incredible base for a Rum Old Fashioned. Here we’ll make it even more decadent by adding it to a jar alongside some browned butter. 

So add unsalted butter to a small pan and gently heat until melted. Keep stirring with a spoon so the solids don’t burn, and as the butter foams the water will evaporate, and you’ll start seeing golden specks at the bottom. That’s where the nutty, toasty flavor comes from, so we’re not straining that out. When the butter fully turns a deep golden brown and smells wonderfully nutty, carefully pour it into the jar.

Keep in mind that the butter will still be hot, so carefully stir to combine. Now seal the jar and place it in a sous-vide bath set to 55°C or 130°F for 4 hours, shaking occasionally. Once the time is up, chill the infusion to room temperature before placing it in the freezer. You’ll see the butter solidify in the jar, making it easier to strain out our buttery rum using a muslin cloth.

Next, let’s make the cacao liqueur, which we’ll do in the same sous vide method. This component will make for the chocolate and vanilla notes of our cookies, along with the sweetness. 

Cacao Liqueur

● 420mL · 14oz Diplomatico Mantuano Rum

● 40g Crushed Cacao Nibs

● 125g Cacao Butter

● 2g Vanilla Bean

● 40g Brown Sugar per 100mL of Liqueur

● 30g Water per 100mL of Liqueur

● 1.5g Gum Arabic per 10g Water (Optional)

Add the rum, cacao nibs, cacao butter, and vanilla bean to a sous vide bag, and don’t forget to split the vanilla bean open and scrape out the seeds to get the most flavor. This time we’re going with Diplomatico’s Mantuano rum as the base, which is a medium-bodied blend, aged for up to 8 years, with notes of dried fruit, vanilla, and a gentle spice. It’s perfect for infusions like this because it gives us a rich backbone while still letting the chocolate shine.

So double seal the bag to avoid any leaks, then place it into the sous vide bath set to 55 °C or 130 °F, and let it infuse for 4 hours, shaking the bag occasionally to keep everything well-mixed. After 4 hours, it’s now time to leave the infusion to cool before placing it in the freezer for the cocoa butter to solidify. Now you can strain the infusion like we did with our buttered rum, then measure the amount–and keep the cocoa butter around as we’ll also need it for the garnish. 

This is because we’re adding in brown sugar, water, and gum arabic based on how much of the infusion we have. If you want to skip the math, you can use my Liqueur Calculators here on kevinkos.com, which are available to all supporters on Patreon. So begin by warming up the water and combine it with the gum arabic, stirring until dissolved. Then we can add in the sugar, and finally the infused rum. 

We have the ingredients for the cocktail, so let’s just quickly run through how to make Jeffrey Morgenthaler’s Chocolate Chip Cookies, which will serve as garnish. 

Chocolate Chip Cookies (Jeffrey Morgenthaler’s Recipe)

● 113g · 0.5 cup · 1 stick Room Temperature Butter*

● 75g Light Brown Sugar

● 125g White Sugar

● 1 Large Egg

● 5mL · 1 tsp Vanilla Extract

● 175g Flour

● 2.5mL · 0.5 tsp Salt

● 2.5mL · 0.5 tsp Baking Soda

● 160g · ~1 cup Chocolate Chips

● 80g · ~0.5 cup Chopped Nuts

First cream the butter and sugars, whisk in the eggs and vanilla, then fold in the dry ingredients. Add the chocolate chips, scoop onto a baking tray, and bake at 250°C or 400°F for ten minutes or until golden brown with a slightly soft center. As a very important last step, sprinkle some flaky sea salt once you take them out.

Now all we have to do is assemble this wonderful cocktail and then it’s the best part: enjoying it.

Chocolate Rum Old Fashioned 2.0

● 45mL · 1.5oz Brown Buttered Rum

● 15mL · 0.5oz Cacao Liqueur

● 3 dashes Orange Bitters

● 6 drops 20% Saline Solution

Chocolate Chip Cookie Garnish with Orange Marmalade

Get you well chilled mixing glass first, and we’ll add in the ingredients while a clear ice block is tempering in a rocks glass. Now add plenty of ice and stir until perfectly chilled and diluted, then strain the cocktail over the large clear ice cube. Garnish with a chocolate chip cookie on the rim, and if you want to take it even further, add a small spoonful of orange marmalade on top of the cookie for a sweet-and-citrusy bonus bite. So now let’s give it a try!

The aroma hits you first with rich cocoa, butter, and a hint of orange. The first sip is decadent: smooth dark chocolate up front, balanced by the warmth of the rum and a bright lift from the bitters. It’s well rounded, with a silky mouthfeel that makes you want to take a sip after sip. Especially when you enjoy it with the cookie. Delicious.

And with that, we wrap up our 4-part Diplomatico cocktail series. We’ve gone from tiki riffs, improved classics, to hot-and-cold creations, and now, a dessert-style Old Fashioned. We had a lot of fun, but it’s now time for you to send your cocktails combining rum and chocolate, and maybe I’ll see you next year in Brazil. 

Learn more about Artisans of Taste here, and if you have a favorite way of adding chocolate to your cocktails let us know in the comments. Cheers!