Combine milk and cream in a medium-sized saucepan over medium-low heat. Stirring occasionally, heat until the mixture reaches a temperature of 170°F and bubbles start to form around the edges. Turn off the heat and whisk in the cocoa powder and 4 oz chocolate until chocolate is completely melted and the mixture is smooth.
While the milk mixture is heating, whisk the egg yolks together until smooth in a heatproof bowl. Gradually whisk in the sugar and salt until well incorporated and the mixture is thick and a pale yellow color. Temper the egg yolks by very slowly pouring the hot milk mixture while whisking constantly. Pour this mixture back into the saucepan and heat, stirring frequently, on low heat to a temperature of 185°F. The mixture should be slightly thickened, enough to coat the back of a spoon. It should not come to a boil.
Pour the custard mixture through a fine mesh strainer into a clean bowl in an ice bath to cool the mixture completely, stirring constantly. Cover and refrigerate at least 4 hours or overnight.
Remove the custard from the refrigerator and whisk in the vanilla extract. Pour the mixture into an ice cream machine and churn for about 20 minutes (follow your ice cream maker directions).
Meanwhile, place the chocolate in a microwave-safe bowl and microwave the remaining 4 oz of chocolate in 20 second intervals, stirring in-between, until it's melted and smooth.
Transfer ⅓rd of the ice cream to an airtight container. Drop some marshmallow creme in spoonfuls, drizzle in a little melted chocolate and add some graham crackers. Repeat process 2 more times. Freeze until solid, about 2 hours.
Use the Best Ingredients – when making ice cream you want to use the best ingredients possible so use free-range eggs and organic milk and cream. Also use high quality products when it comes to added flavorings like vanilla or chocolate. Never use imitation vanilla.
Don’t Cut the Fat and Calories – ice cream is not the dessert that you should be cutting the fat. It depends on the high-fat content to create a creamy texture. If you go lower fat, it will cause an icy ice cream. If you’re on a diet, just have a smaller scoop!
Chill the Custard – you don’t necessarily need to chill the custard overnight, but you want to chill until it is as cold as possible.
Use Frozen Bowl – make sure your ice cream bowl has been frozen for at least 24 hours, otherwise you aren’t giving ice cream a great chance to freeze.
Start Ice Cream Motor First – do not pour the custard in the frozen bowl before starting the ice cream maker. It will start freezing upon contact. You want the motor running and slowly pour the custard in.
Don’t Overchurn – always error on the side of caution when it comes to churning your ice cream. You do not want it to be hard. Remember it will continue to freeze once you place in the freezer.
Keep It Creamy – homemade ice cream can turn hard as we don’t add preservatives, however Xanthan gum or a couple tablespoon of vodka will help keep it creamy.