Place the milk, cream and ¼ cup of the sugar in a small pan and cook over low heat, whisking from time to time, until it is warm, about 175°F.
Place the egg yolks, ¼ cup of the sugar, the vanilla extract and salt in a small metal bowl and whisk until completely mixed.
Add ¼ cup of the warm milk mixture to the eggs, whisking all the while.
Continue adding milk to the eggs, ¼ cup at a time, until you have added about 1½ cups.
Slowly, whisking all the while, return the now milk and egg mixture to the remaining milk mixture in the pan and continue cooking until it just begins to thicken or reaches about 185°F.
Do not allow the mixture to boil.
Pour through a medium fine strainer into a metal bowl, discard the solids and set aside until it reaches room temperature.
Cover and refrigerate until it reaches 40°F, about 3 hours. Transfer to an ice cream maker and proceed according to the manufacturer's instructions.
When the ice cream is just beginning to come together but has not hardened completely, add the marshmallows, pecans, chocoloate chips, and coconut, if desired, and process for about 5 more minutes.