Bunch foil around the base of the safety cones and stand them in muffin tins. Set aside.
Yellow Cake: Whip the egg whites in a clean bowl until stiff not dry and place in the refrigerator while you make the rest of the batter. Cream the butter and add the sugar. Continue mixing to blend well. Add the extracts and mix well. Sift the flour 3 times with the baking powder then add it to the butter mixture alternately with the milk in 3 additions. Fold in the whites. Pipe or spoon the batter into the cones, filling about 3/4 of the way up. Bake at 350 degrees F for 20 to 25 minutes until batter is firm to the touch in the center. Let cool.
Chocolate Sour Cream Cake: Preheat the oven to 350 degrees F. In a mixer fitted with a whisk attachment (or using a hand mixer) cream the butter until smooth. Add the sugar and eggs and mix until fluffy, about 3 minutes. Add the vanilla, cocoa, baking soda and salt; mix. Add half of the flour, then half of the sour cream, and mix. Repeat with the remaining flour and sour cream. Drizzle in the hot coffee and mix until smooth. The batter will be thin. Pipe or spoon the batter into the cones, filling about 3/4 of the way up. Bake until the tops are firm to the touch and a toothpick inserted into the center comes out clean (a few crumbs are okay) about 35 minutes.
To make the frosting place all the ingredients except the vanilla in the top of a double boiler (not over the heat yet). Beat with a mixer thoroughly. Place over boiling water and beat continuously until the frosting is stiff and holds peaks. Take off the boiling water and add the vanilla then continue beating until cool. Frost the top and dip/roll in sprinkles if desired.