Tuna Mix**

Mix tuna, mayo, onion, and pickle together in a bowl, set aside.

Chicken Base**

Cover a chicken breast with a piece of cling wrap and flatten it with a meat tenderizer. Put it in the oven on a cookie sheet with a piece of parchment paper under the chicken. Cook at 350f until cooked through, around 15 minutes (I check it with an instant-read thermometer to be sure).

Assembly**

Leave the chicken on the cookie sheet, cover with the tuna mixture and a slice of the cheese of your choice (I used marble).

Switch the oven to high broiler, put back in for a couple minutes until the cheese is melted and bubbly, then remove.

Final**

Place 3Tbsp guacamole on the plate, then stick the finished melt on the guac and eat it!