Cindy's Mom Texas Sheet Cake | Flavor and Friends

Ingredients

• For cake
• 2 cups all purpose flour
• 2 cups sugar
• ½ teaspoon kosher salt
• 1 teaspoon baking soda
• 1 cup unsalted butter
• 3 tablespoons cocoa powder
• 1 cup water
• ½ cup vegetable oil
• 2 eggs, lightly beaten
• ½ cup buttermilk (or sour cream)
• 1 teaspoon vanilla
• For icing
• ½ cup unsalted butter, cut into pieces
• ¼ cup cocoa powder
• 6½ tablespoons whole milk
• 1 teaspoon pure vanilla extract
• 16 ounces confectioners' sugar
• 3 cups mini marshmallows