Eggnog Cupcakes with Spiced Rum Caramel

Place the sugar and water in a medium size heavy bottom sauce pan. Swirl the pan until the sugar is immersed in water.
200 grams granulated sugar, 60 mL water
Place the saucepan over medium heat and allow the sugar to fully dissolve in the water, gently swirling the pan every minute or so.
Bring the sugar and water to a simmer and lower the heat to low. Place the lid on the pan and allow the mixture to simmer until the color begins to darken to a light amber color, this should take about 10 minutes. Make sure to remove the lid and check the color at least every minute or so.
You can gently swirl the pan every couple of minutes but DO NOT STIR IT WITH ANYTHING. If there are crystalized pieces of sugar on the sides of the pan, the steam running down from the lid should dissolve them but if it doesn’t, you can use a pastry brush wet with water to brush them away.
Once the sugar is a dark amber color, remove it from the heat and add the butter. Use a whisk to mix in the butter until it's smooth and then pour in the heavy whipping cream while stirring constantly.
85 grams salted butter room temperature, 60 mL heavy whipping cream room temperature
Now add the rum and the salt and whisk until it's smooth.
60 mL spiced rum, 1-2 tsp fine sea salt
Pour the caramel sauce in a heat proof jar, cover and set aside to cool completely to room temperature.

In a small saucepan, combine the sugar, flour and salt. Whisk until they're well distributed.
grated nutmeg *optional, 100 grams granulated sugar, 30 grams all-purpose flour spooned and leveled, Tiny pinch of salt, 1/2 tsp ground cinnamon*
While whisking, slowly pour in the eggnog and whisk until the mixture is smooth.
120 mL eggnog
Place the saucepan over medium heat and stir continuously (but not too aggressively) for 3-5 minutes.
When the mixture thickens and begins to hold streaks, whisk quicker for about another 30-60 seconds. It should be thick like custard.
Pour the mixture into a heat safe container, cover it and allow it to cool to room temperature.

Preheat the oven to 350F/177C convection and line 13 muffin tins with cupcake liners (preferably a light colored pan).
In a medium bowl, whisk together the cake flour, baking powder, salt and sugar until they're evenly distributed (whisk well).
180 grams cake flour spooned and leveled, 1 1/2 tsp baking powder, 1/4 tsp fine sea salt, 175 grams granulated sugar
Add the oil and butter to the dry ingredients and beat together until they're combined. Add the egg and vanilla extract and mix until they're fully combined.
60 mL canola oil or any neutral oil, 56 grams unsalted butter room temperature, 1 large egg room temperature, 1 tsp pure vanilla extract
Add the sour cream and turn the mixer to low speed, while streaming the eggnog in. Scrape the edge of the bowl and mix just until the cupcake batter is smooth.
113 grams sour cream room temperature, 78 mL eggnog room temperature
Fill each cupcake liner about 2/3-3/4 full, about 50-55 grams of batter per cupcake.* You might have enough batter for about half a cupcake leftover. DO NOT BE TEMPTED to distribute that among the cupcakes, they will sink if they’re overfilled.
Bake for 18-20 minutes. They are done when you press on the center of the cupcake and it springs back or when a toothpick inserted comes out clean.
Remove them from the oven and let them cool in the cupcake pan for 10 minutes, then move them to a cooling rack. Allow the cupcakes to cool completely before frosting.

Once the custard portion for the buttercream has cooled completely, place the butter into a large bowl or the bowl of a stand mixer.
240 grams unsalted butter** room temperature
Use a hand mixer or a stand mixer, with the whisk attachment, to beat the butter at full speed for 5 minutes. Make sure to scrape the edge of the bowl every so often.
When the butter is pale and fluffy, add the cooled custard in 3-4 increments, with the mixture running at medium-high speed.**
Add the vanilla and mix until it's fully combined and smooth.
1 tsp vanilla bean paste
To remove any excess air for smooth piping, you can switch to a paddle attachment and mix on low speed for a few minutes *optional.

Use a piping bag fit with a large round piping tip to frost the cupcakes. Try to leave a small hole in the center (see photos) for the caramel to drip into.
Use a spoon or a piping bag with a small round tip to drizzle the caramel into the center of the frosting.
Top with grated nutmeg and serve fresh or just slightly chilled.
1/2 tsp ground nutmeg*