2 cups root beer* (NOT diet - don't say I didn't warn you)
1 cup dark unsweetened cocoa powder
½ cup (1 stick) unsalted butter, cubed
1¼ cup granulated sugar
½ cup firmly packed brown sugar
2 cups all-purpose flour
1¼ teaspoons baking soda
1 teaspoon kosher salt
2 large eggs, room temperature, lightly beaten
*You can replace ½ cup of this with root beer schnapps if you can find it for a stronger root beer flavor; I would also recommend using 1 teaspoon of root beer extract, if you have it.
2 ounces (about ⅓ cup) dark chocolate, melted and cooled slightly
½ cup (1 stick) unsalted butter, room temperature
1 teaspoon kosher salt
¼ cup root beer
⅔ cup dark unsweetened cocoa powder
2½ cups confectioners' sugar