If using wooden skewers, soak them in water for 20 minutes or more prior to grilling.
Cut each chicken breast into a few pieces. Roughly chop the vegetables and mince the garlic. Combine the seasoning mix and set aside.
In food processor process the vegetables until minced (but not a paste), scraping the sides down once or twice. Remove to a mixing bowl. Stir in the spice mixture, eggs, and bread crumbs. Set aside.
Add the chicken to the processor and process until ground into very small pieces. Transfer to the mixing bowl, and fully incorporate into the vegetable mixture. (I find this easiest to do with my clean hands.)
If the mixture is too soft to mold onto the skewers at this point, mix in the remaining bread crumbs. Shape the kabobs onto the skewer, using about 1/3 of a cup of the chicken mixture per skewer. You can eyeball this, but if you make them too big they may droop from the skewer. It took me one or two to get a feel for forming the mixture onto the skewer so it stayed.
Grill over low heat, turning and cooking evenly until just cooked through, taking care not to overcook. Exact time will depend on size of kabobs and precise level of heat. Remove to a platter, and brush with the optional melted butter/olive oil mix.