Preheat the oven to 350°F. Grease and flour two 9-inch round cake pans. In a large mixing bowl, combine flour, cocoa powder, baking powder, baking soda, and salt. In a separate bowl, beat together the butter and sugar until creamy. Add eggs one at a time, then mix in milk, oil, and vanilla. Gradually add dry ingredients to the wet mixture. Divide batter between pans.

Place the pans in the oven and bake for 25-30 minutes or until a toothpick inserted comes out clean. Let the cakes cool in pans for 10 minutes, then transfer to a wire rack to cool completely.

In a large bowl, beat the butter until creamy. Gradually add powdered sugar, followed by marshmallow fluff and vanilla extract. Beat until frosting is light and fluffy.

Place one cake layer on a serving platter. Spread frosting on top and sprinkle with graham cracker crumbs and chocolate chips. Place the second layer on top and cover with remaining frosting. Toast the frosting with a kitchen torch if desired.

Cut the cake into 8 slices. Serve with a scoop of vanilla ice cream or a glass of milk for a complementary treat.

Store leftover cake in an airtight container at room temperature for up to 3 days. For longer storage, refrigerate for up to a week or freeze for up to 3 months.