2 1/2 cups flour
2 cups sugar
5 tablespoons unsweetened cocoa powder
1/2 teaspoon salt
2 large eggs, room temperature
1 teaspoon vanilla extract
1 cup vegetable oil, room temperature
1 cup buttermilk, room temperature
2 teaspoons baking soda
1 cup hot water
1/2 cup sugar
1/3 cup milk
2/3 cup solid vegetable shortening
1/4 teaspoon salt
1 1/2 teaspoon vanilla extract
1 1/2 cups sugar
6 tablespoons milk
6 tablespoons butter
4 large marshmallows, cut in pieces
1/2 cup semi-sweet chocolate chips
Combine flour, sugar, cocoa, and salt in large mixing bowl. Add eggs, vanilla extract, oil and buttermilk, blending well with electric mixer. Set aside.
Stir baking soda into hot water and add to batter, mixing well (batter will be thin).
Pour batter into paper-lined muffin cups, filling 2/3 full. Bake at 350° F for 15 to 20 minutes or until tops spring back when gently touched. Cool in pan on wire rack for 5 minutes; remove from tins to cool completely.
Combine sugar, milk, shortening, salt and vanilla in small mixing bowl. Beat with electric mixer at high speed for 5 minutes or until fluffy.
Fill decorator tube with filling. Insert tip into center of cupcake and squeeze until filling comes to top.
Boil sugar, milk and butter together in small saucepan for 1 1/2 minutes, stirring occasionally.
Remove from heat and stir in marshmallows and chocolate. With portable electric mixer, beat until smooth and thick, about 5 minutes. Frost the filled cupcakes.