When I make cupcake cakes. I use a 60 ml scoop to fill the liners. This ensures they all have roughly the same amout of batter. In addition, I found this amount worked perfectly for me and I did not have the hump.

Once my cupcakes are baked, I arrange them on my baking sheet so they interlock. This eliminates those big gaps. Once I am happy with the arrangement I put a small dab of icing on the bottom of the liner and affix the cupcake to the board.

To cover the cupcakes, I use my spatula. You may prefer to use the icer tip #789. Decorate the top and add your border.

When serving the cupcake cake, lift each individual cupcakes straight up. This keeps all the icing from that cake on with out ripping it off of the adjacent cupcakes.

Hope this helps.

Cake_Princess