Root Beer Cake

Cake:
1 1/4 cups all-purpose flour
1/2 teaspoon baking soda
Pinch salt
1 cup root beer (do not use diet)
3/4 cup packed light brown sugar
1/2 cup (1 stick) unsalted butter, softened
2 large eggs
2 teaspoons pure vanilla extract

Frosting:
6 tablespoons root beer
1 1/4 cups confectioners' sugar
1/4 cup ( 1/2 stick) unsalted butter, softened
1/2 teaspoon pure vanilla extract

Heat oven to 350 degrees. Grease an 8-inch springform pan.

For cake, sift together the flour, baking soda and salt; set aside. Put 1 cup root beer in a small saucepan; boil, uncovered, until it is reduced to 1/2 cup, about 5 minutes. Cool to lukewarm.

Beat brown sugar and butter in large bowl of an electric mixer on high speed until light and fluffy, about 2 minutes. Add the eggs, one at a time, mixing well after each addition. Stop the mixer and add the reduced root beer and vanilla. Mix just to combine. Fold in the dry ingredients with a rubber spatula.

Transfer batter to prepared pan. Bake until a toothpick inserted in the center comes out clean, 45 to 50 minutes. Cool 5 minutes. Poke holes all over top with a toothpick. Brush with about 3 tablespoons of the root beer. Remove the sides from the pan and cool cake completely.

For frosting, mix remaining 3 tablespoons root beer, confectioners' sugar, butter and vanilla in a small bowl to make a thin frosting. Spread over top of cooled cake, letting it drip down the sides.