In a saucepan over medium-low heat, whisk together cream, milk, cocoa powder, brown sugar, vanilla extract, and a pinch of salt. Bring the mixture just to a boil.
While the cream mixture is heating, use an immersion blender to whip the egg yolks and white sugar until it’s pale and thick.
Whisking the cream mixture constantly, slowly pour in the egg mixture until it’s well-combined. (I used the immersion blender for this as well.)
Stir, and allow the mixture to thicken for a couple minutes. Strain the mixture to eliminate any clumps and place in an airtight container. Put it into the refrigerator for a few hours, until completely chilled. (If in a hurry, place in the freezer for 1 hour. Don’t forget about it!)
Once the mixture is chilled, pour it into an electric ice cream maker and churn for 20+ minutes to your desired consistency. Finally pour in the pretzel pieces and churn another minute.
Serve immediately or place in the freezer to harden.