Moka coffee is a very Italian thing. When I see Americans making coffee with capsules, or French with filters, I always think: "you don't know what you're missing". Moka is different. It's not just the flavor — it's the ritual. Filling the tank, the filter with finely ground coffee, screwing the two halves together, low heat, and that characteristic gurgling when steam pressure pushes water upward.
For coffee gelato, moka is the right choice for two technical reasons. First: it extracts oils and natural emulsifiers from coffee (the "crema" under pressure), which help the gelato's creaminess. Espresso from a bar is even better for this, but requires a dedicated machine; home moka does a 90% comparable job.
Second: moka coffee has a much more concentrated water/coffee ratio than American filter coffee. A small cup (35-40 ml) has the same caffeine and aromatic compounds as a large cup of American coffee. For gelato this is perfect: we add little "free" water but lots of flavor.
Adding mascarpone is the second secret. Mascarpone is a very fatty (44%) and very creamy fresh cheese, typical of Lombardy (my region). In gelato shops it's used as a natural emulsifier for "super creamy" gelatos. In coffee gelato it balances the coffee's acidity and gives that velvety mouth feel typical of tiramisu.
A technical note: the coffee must be COMPLETELY cold before adding to other ingredients. If still warm, it will partially melt the cream and mascarpone fats, and you'll get a "broken" base that struggles to freeze well. Better to make the coffee the evening before and put it in the fridge — it'll be perfect in the morning.
