Combine the heavy cream, milk and instant coffee in a medium saucepan and place over medium heat.

Heat until small bubbles start forming at the edges, 4 to 6 minutes, then turn off the heat, stir and cover.

Let steep for 1 hour.

Meanwhile, place the Oreos into a food processor (if you will be making truffles with the rest of the oreos, might as well make it easy on yourself!)

Strain the steeped heavy cream mixture through a fine-mesh sieve into a bowl; discard the remnants.

Rinse the saucepan and return the cream mixture to the saucepan.

Whisk in the brown sugar and salt until dissolved.

Heat over medium heat until the mixture just starts to simmer, 3 to 5 minutes, Remove from the heat.

Nest a large bowl in another large bowl of ice water; set aside.

Whisk the egg yolks and granulated sugar in a medium bowl.

Ladle some of the hot cream mixture into the egg mixture, whisking to avoid scrambling the eggs; repeat until half of the cream mixture has been added, then pour everything back into the saucepan.

Return the saucepan to medium heat.

Cook, stirring constantly with a rubber spatula, until slightly thickened and the mixture coats the back of a spoon, 5 to 8 minutes. (It should register 180° on an instant-read thermometer.)

Immediately strain through a fine-mesh sieve into the bowl set in the ice bath.

Stir in the vanilla.

Stir occasionally until the custard is cooled about 15 minutes.

Cover and refrigerate until very cold, 4 hours to overnight.

Place a metal loaf pan in the freezer.

When you're ready to churn, pour the custard into an ice cream maker and churn according to the manufacturer's instructions until it's the consistency of soft serve, 25 to 35 minutes.

Add the crushed Oreos and continue churning for 1 minute to combine.

Scrape into the chilled loaf pan.

Press plastic wrap directly onto the surface and freeze until firm,

6 hours to overnight.