Sift flour, cinnamon, nutmeg, salt, baking powder, and baking soda.
Grease a 8” cake pan, you can use a round piece of parchment to line the bottom of the pan.
Pre-heat oven to 350F.
Cream butter at medium-high speed for 1 minute.
Add oil and mix on low.
Add sugar and cream for 2 minutes.
Add eggs, one at a time. Incorporate the first egg before adding the next.
Add eggnog, vanilla, and rum if using. Stir to combine.
Add dry ingredients to the batter and mix until incorporated.
Pour onto cake pan.
Bake for 20-30 minutes, rotating the pan halfway.
The cake will be ready when you insert a toothpick and it comes out clean. Or even better, you can simply touch the surface of the cake with your finger, if it springs back, it means your cake is done.
If cake is browning too fast on top but not baked inside, simply cover it with some foil to finish baking.
White Chocolate Eggnog Mousse
Place white chocolate chips in a bowl.
Heat heavy cream and eggnog in a small saucepan until almost come to a boil. You can alternatively use the microwave to do this.
Pour hot cream over white chocolate.
Let it sit for 2 minutes.
Stir with a spatula until all the white chocolate has melted.
If there are still bits of white chocolate that haven’t melted, simply place bowl in the microwave for a few seconds at a time, stirring in between, until every bit of chocolate has melted. Be careful not to overheat the chocolate in this process.
Let this eggnog ganache cool down all the way, on top of the counter.
Add mascarpone cheese to the eggnog mixture. Whisk until completely incorporated. You can use a mixer to do this, just be careful not to overwhip.
Eggnog Cream Cheese Frosting
Place cream cheese and butter in the bowl of an electric mixer. Cream at medium-high speed for 2 minutes.
Add powdered sugar with the mixer off.
Mix on low until combined.
Increase speed to medium-high and cream for 1 minute.
Add 2 tablespoons of eggnog. Mix to combine.
Check the consistency. If you want to, you can add more powdered sugar if consistency is too runny, or add more eggnog if consistency of frosting is too stiff.
Slice cake in half.
I used a tall 8” cheesecake pan to do this. You can use any pan you want, but a springform pan will help your mousse shape nicely in the filling.
You can simply spread the filling on top of the cake if you will.
Refer to post above for pictures and instructions.
I lined the sides of my cheesecake pan with some parchment paper strips.
Place the first cake layer on the bottom of the pan.
I used a bit of simple syrup to keep my cake moist*.
Spread mousse over first layer.
Top with next layer.
Use more simple syrup to glaze the top layer.
Stick cake in the fridge for at least a few hours so the mousse can firm up.
Frost cake with the Eggnog Cream Cheese Frosting.
I used desiccated coconut to coat the sides of the cake for a pretty winter look.
Cake will keep in the fridge for a few days, as long as you used pasteurized eggnog.
*Simple syrup is equal parts of sugar and water brought to just a boil, and then cooled down. I use it to brush on my cakes to keep them moist.