If you are making the ice cream:
Combine the cocoa powder and the sweetened condensed milk in a large saucepan over medium heat. Whisk to combine and to break up any clumps. Bring to a simmer and then add the whole milk and heavy cream. Stir occasionally for about 5 minutes and then remove from heat.
In a large bowl, whisk the eggs yolks until they are light in color. Slowly add in the sugar and whisk to combine. At this point, the mixture should be on the thicker side. Now slowly temper the cocoa/cream mixture into the egg mixture by adding 1/2 cup of the cocoa/cream mixture at a time. Once about half of the cocoa/cream mixture is tempered in, you can transfer the egg mixture into the saucepan with the remaining cocoa/cream mixture. Cook the mixture over low heat, stirring frequently, until the mixture thickens slightly. Remove from heat and pour into a container. Allow for the mixture to sit at room temperature for about 20 minutes. and then cover and refrigerate for 2-4 hours.
At this point, make sure you have done all of the necessary preparations for your ice cream machine (for example, make sure the container has been frozen and everything is ready to go). Now pour the mixture into your prepared ice cream machine and process per your manufacturer''s instructions. This should take about 25-30 minutes depending on your ice cream maker.
Taking your now churned ice cream, transfer to a freezer safe container. Gently fold in the dark chocolate chunks, chocolate-covered pretzels, marshmallows and nutella and mix until the ingredients are evenly dispersed.
**Note** If you are using a store-bought ice cream. Remove the ice cream from the freezer and let stand at room temperature for about 15 minutes before you begin mixing in your fillings.
Cover the freezer safe container with an airtight lid and freeze until the ice cream has reached the frozen consistency you desire.
You may eat the ice cream without putting it straight into the freezer, but it will be more like soft-serve.
The ice cream will keep in the freezer for a couple of weeks to a month. Enjoy!