This is a very easy meal to prepare. I generally will give my toddler a small bowl of this zucchini and then something else (like grain, pasta, etc.), for a nice, balanced meal.
I buy organic zucchinis so I feel comfortable using the skins in the recipe. I slice up a few zucchini, mixing yellow squash ("summer squash") in there as well. I usually slice them not too thin, and then quarter the slices to make good bite size pieces.
I then toss the zucchini in a small steamer that I have. I add some spices just to season a little. You can use whatever you think might taste good! Just be careful that the spices are fine enough so that they don't pose a choking hazard (something like pieces of rosemary might be too big). Also, if you use a seasoning blend (like an Italian herb grinder as shown in my photo), it might have a lot of salt in it, so just check the ingredients. And of course be sure it doesn't have too much pepper (black pepper or hot red pepper!).
I basically steam the zucchini until soggy. When my toddler was just starting on solids, I more or less minced the zucchini, but at this point I can make it a little firmer and she will eat it with a fork.
I freeze this in baby food jars or small glass bowls, and it reheats fine, although it does tend to release some more liquid from the zucchini, but I just drain the extra liquid so it isn't messy.