When it comes to making nutty ice creams, my favorite way to achieve flavor is with an overnight infusion of toasted nuts in the milk and cream used in the recipe, rather than incorporating nut pastes or butters into the ice cream base. Time and heat help draw out the aromatic essential oils in the nuts, giving dairy a robust flavor even after the nuts have been strained out.
Part of this is about cost and quality control, the rest comes down to issues both textural and philosophical. It's easy to find cheap nut pastes and butters, but the texture and quality of these affordable store-bought products aren't always the best; freshness and sugar content can vary, while some may be partially defatted to prevent separation. Meanwhile, high-end versions may be silky smooth thanks to wet-milling or conching techniques used to process the nuts, but they also come with eye-popping price tags.
In many dessert applications, churning out a batch of homemade nut paste would split the difference between cost and quality, but I find it to be a labor intensive project that produces a rustic texture, one that isn't ideal for ice cream. And besides, when a frozen dessert craving strikes, the idea of having to tackle such a time-consuming initial step can be as much of a bummer as waiting around for a special order of fancy nut butter or paste to show up at your front door.
I prefer to make ice creams that don't require specialty ingredients, or fancy equipment, aside from an ice cream machine. All you really need for great nutty ice creams are whole nuts, of the best possible quality, that get toasted and skinned.
In my cookbook, I take a one-size-fits-all approach for nutty ice creams, employing a technique that can be used with everything from black walnuts to cashews, peanuts to pine nuts. It's an adaptable recipe that'll get the job done with a wide variety of ingredients, but here I'm tailoring that approach to bring out the best in one specific type of nut: hazelnuts.
I start out by roughly chopping toasted, skinned hazelnuts. This optimizes their surface area, allowing their flavor to readily infuse in the milk and cream. The key here is surface area "optimization" rather than maximization.
Finely chopping or even grinding the nuts, whether into a paste or a butter, would truly maximize their surface area. However, this would also cause the nuts to absorb far more of the milk and cream, resulting in a final product that's closer to a purée than an infusion. For that approach to work, the nuts would need to be processed to a truly buttery consistency or else the finished ice cream would end up grainy and coarse.
What I want is to chop the hazelnuts just enough to facilitate the infusion without allowing for excess absorption. The same principle is used for cutting mirepoix for chicken or beef stock—if you chop the vegetables too finely, they will absorb too much liquid, leaving you with a lower yield of stock. Without being too prescriptive, I'd say to aim to chop each hazelnut into quarters, but there's no need to cut each nut one by one; running a knife over them for a rough chop will do just fine.
After chopping, I transfer the hazelnuts to a 3-quart stainless steel saucier before adding the milk and cream.
When I feel like splurging, I'll toss in a split and scraped vanilla bean as well (it's important to set aside the scraped vanilla seeds at this stage, as they would otherwise cling to the hazelnuts and be lost with straining later on). This is also a good occasion to wring out everything you can from a leftover vanilla bean. The mellow, almost oaky flavor the pod can give up with an infusion echoes the nutty, creamy quality of the hazelnuts in a lovely way, but if you don't have a pod (fresh or otherwise) on hand, simply leave it out.
The hazelnut and dairy mixture, with or without a vanilla pod, is brought to a simmer over medium heat, then covered and cooled to room temperature. From there, I'll refrigerate it overnight or up to 36 hours; anything past the 12 hour mark is less about flavor than convenience, so move the project forward at whatever pace works best for you.
After refrigeration, I return the mixture to a simmer once more, to ensure the layer of butterfat that congeals around the hazelnuts has fully melted and that the nuts have expressed as much flavor as possible. I then strain the hazelnuts through a fine mesh sieve, stirring and pressing gently to prevent any flavorful dairy from being left behind; the hazelnuts will still be quite firm, so there's not much to press out.
While the ice cream base itself has no further need for these hazelnuts, there's no need to toss them in the trash. They can be re-purposed, as-is, in our creamy or crunchy Homemade Nutella. The recipe won't require any modification, but do be aware the cooking process will take a little longer thanks to the added moisture in the hazelnuts. Of course, the finished product will be milder in flavor than one made with fresh hazelnuts, but with all that added chocolate and hazelnut oil, homemade Nutella will still be nuttier and tastier than its store-bought equivalent.
Once the saucier has cooled to the touch, I'll add my eggs and sugar (toasted sugar is a particularly nice option here), along with the reserved vanilla seeds from the bean I scraped the day before, and then whisk in the warm hazelnut milk. At this point, the mixture won't be hot enough to scramble the yolks, so there's no need for any sort of tempering.
Next, I whisk in a little mascarpone into the base.
Mascarpone has a naturally sweet and faintly nutty character that seems to amplify the flavor of the hazelnuts, and it also serves to top off the dairy content of the ice cream (as the hazelnuts themselves can absorb quite a bit).
I start the ice cream base over medium-low to gently warm the eggs, stirring and scraping all the while with a flexible, heat-resistant spatula. When the mixture is warm to the touch, I increase the heat to medium and cook (always while stirring and scraping) until steaming-hot. The ideal cooking temp for any given ice cream will vary from recipe to recipe, depending on the percentage of sugar and dairy, as well as the degree of coagulation and/or evaporation a baker is aiming for in the base.
It's not something I generally monitor with a thermometer myself, but for those who'd be more comfortable doing so, aim for something like 165°F (74°C), then strain the base through a fine-mesh strainer (it's fine to use the same one from before, no need to wash it out between uses).
Finally, I flavor the ice cream with a shot of Frangelico, but any nutty or complementary flavor of liqueur will do, or simply use an equal amount of a good vanilla extract to head in a different direction. Because alcohol-based extracts deliver a different complement of vanilla compounds than a dairy-based infusion, I don't like to increase the extract when not using a pod (or conversely, omit the extract when using a pod). I see extracts and beans as different delivery mechanisms for different batteries of flavor, rather than interchangeable parts.
As with any ice cream base, after the initial round of seasoning with salt and liqueur or vanilla, I like to sample the base and adjust it to taste from there. Do bear in mind ice cream will taste less sweet once frozen, so don't overdo it on salt.
The penultimate step is to chill the ice cream base down to 39°F (4°C) before churning. This can be done proactively over an ice bath, or passively in the fridge (with the ice cream base covered, to prevent odor absorption and excess moisture loss through evaporation). As former Serious Eats ice cream whisperer Max Falkowitz has explained here, ice cream bases don't need to be chilled overnight, so long they are properly chilled before churning.
While my go-to recommendation for an ice cream machine is the Cuisinart Ice 21, I used the Breville Smart Scoop here as I needed to churn up several quarts of this ice cream for....personal reasons. For more information about these machines, check out our complete ice cream maker review.
After churning, the ice cream can be enjoyed straight away as soft serve, or transferred to a chilled container to freeze completely for scooping.
In photos, the hazelnut ice cream looks deceptively beige, like plain vanilla, but on closer inspection, it has a warm ivory color from the hazelnut infusion, the only subtle hint of the flavor inside.
Thanks to the mascarpone, the ice cream has a sweet richness and complex dairy flavor to underscore its nuttiness, making it an ice cream worth savoring on its own. That said, it pairs especially well with mild and creamy fruits like bananas or figs, with a sprinkling of toasted hazelnuts for crunch.
Or, when I'm feeling particularly extra, I'll top it with a spoonful of warm, homemade Nutella for a hazelnut sundae like no other.