Cake:
2 1/8 cups all-purpose flour
1/2 cup unsweetened cocoa
1 teaspoon baking soda
1/2 teaspoon salt
1 1/2 cups sugar
1 1/2 sticks (12 tablespoons) butter, softened
1 oz (1 bottle) red food color
2 large eggs
2 teaspoons vanilla
4 teaspoons vinegar
1 cup milk
Frosting:
2/3 cup milk
2 tablespoons all-purpose flour
1/4 teaspoon salt
2/3 cup sugar
1 1/4 sticks (10 tablespoons) butter, softened
1/2 teaspoon vanilla
Heat oven to 350 degrees.
Grease 13x9 pan.
Add 1 tablespoon of vinegar to a measuring cup, then fill with milk to the 1 cup mark. Allow to sit for at least 5 minutes.
Combine flour, cocoa, baking soda, and salt in bowl and stir to mix. Set aside.
Using a mixer, beat sugar and butter together in a large bowl at medium speed, until creamy.
Add food color, eggs, and vanilla and mix well.
Gradually add flour mixture alternately with milk mixture while mix at low speed, until well mixed.
Pour cake batter into prepared pan.
Bake 35-40 minutes or until toothpick inserted in center comes out clean.
Allow to cool completely before frosting.
Combine milk, flour, and salt in a saucepan.
Cook over medium heat, stirring constantly, until mixture comes to a boil (4-6 minutes).
Boil for 1 minute, then remove from heat.
Cover surface with plastic wrap and cool at least 1 hour.
Using a mixer, beat sugar, butter and vanilla together in a bowl at medium speed, until creamy.
Gradually add cooled flour mixture while still mixing, until light and fluffy.
Frost cooled cake.