Line an 8 inch square pan with parchment paper. Set aside.
In a medium sized pot over medium high heat, combine 2 cups sugar, 1/2 cup butter, and 3/4 cup eggnog. Allow to come to a full boil while stirring to avoid scorching until the mixture reaches 234°F. As soon as the mixture hits temperature, remove it from heat and stir in the 11 ounces white chocolate chips until it has fully melted. Add the one 7 ounce jar marshmallow crème, 1 teaspoon vanilla extract, and 1/4 teaspoon ground nutmeg. Stir until smooth.
Immediately pour into prepared pan and allow to fully cool at room temperature. When ready to cut, transfer to a cutting board and use a sharp knife to cut into 10x10 rows. You can soak the knife in a glass of hot water and wipe clean in between cuts, if desired.
Store in an airtight container in the refrigerator or freeze. Best if eaten within three weeks.