Caramel-Stuffed Chocolate Cupcakes

butter (at room temperature)

granulated sugar ((2/3 cup))

brown sugar ((2/3 cup packed))

eggs (at room temperature)

vanilla extract

buttermilk ((1 cup), at room temperature)

sour cream ((1/2 cup), at room temperature)

water or brewed coffee

all-purpose flour ((1¾ cups))

unsweetened cocoa powder ((1 cup) sifted)

baking soda

salt

water ((1/4 cup))

light corn syrup ((1/2 cup))

granulated sugar ((2 cups, plus more for rolling))

heavy cream ((1½ cups))

unsalted butter (cubed (1/2 cup))

sea salt

vanilla extract

pasteurized liquid egg whites ((1/2 cup))

powdered sugar ((4 cups))

salt

unsalted butter (at room temperature (4 sticks, or 2 cups))

vanilla extract

Chocolate Caramel Skulls ((or other edible toppers))

gold sparkling sugar