To prepare an ice bath, fill a large bowl halfway with ice cubes; toss kosher salt generously among the cubes, and add a bit of water. Set aside.
Place the chocolate in a large heatproof bowl. Bring 1/2 cup of the cream to a simmer. Pour the cream over the chocolate
Let it sit for several minutes, then slowly stir the cream into the chocolate. Once it’s smooth, add the cocoa powder to the chocolate cream. Set aside.
Heat the milk and remaining 1/2 cup of cream to a simmer in a saucepan. In a bowl, blend together the egg yolks, sugar, and a pinch of salt with a wooden spoon until thick and light, being careful not to make the mixture foamy.
Whisk in half the hot milk, then whisk the mixture back into the remaining milk. Heat gently, stirring constantly with a wooden spoon. Add the coffee.
Continue stirring the custard until the mixture is thick enough to coat the back of the spoon and it reaches 180°F on an instant-read thermometer.
Remove from the heat and immediately strain into a bowl through a fine mesh sieve. Add the reserved chocolate mixture to the strained custard and stir to combine.
Place the mixture over the ice bath and chill until completely chilled.
Add the NUTS and the chilled custard into the bowl of an ice cream maker and churn according to the manufacturer’s instructions.