Proof yeast by adding warmed eggnog to bowl with yeast and sugar in stand mixer bowl. Let set for 5 mins.
Whisk sourdough discard and egg together
Add flour, softened butter, and salt. Mix dough until it comes together. Continue mixing dough until is soft, not too sticky, and pulls clean away from bowl.
Cover bowl with plastic wrap and let rise for 1-2hrs in a warm spot.
Mix the butter, brown sugar, cinnamon, allspice, and eggnog in a bowl. Set aside.
Get out 9x13 baking dish and lightly grease.
When dough is doubled rolled out on lightly floured surface into a large rectangle (roughly 18x12 inches).
Spread the soften butter mixture on the rolled out dough.
Roll dough up tightly and pinch dough together to secure seam.
Cut into 12 pieces and put in baking dish.
Cover with plastic and let rise for 45 mins.
Preheat oven to 350
After the 45 min rise pour 1 cup heavy whipping cream over the cinnamon rolls. Put in oven and bake for 25 mins.
While the cinnamon rolls cook prepare the cinnamon cream cheese frosting in stand mixer.
Once cinnamon rolls are done, take out of oven and let cool for 10 mins before adding cinnamon cream cheese frosting.