Over medium heat, heat 1 tablespoon butter in a large skillet until melted and bubbly. Add peppers, zucchini and jalapeno; Cook, stirring frequently, until tender, 2 to 3 minutes.Add broccoli and stir to coat. Add ¼ cup water, cover the pan and cook until the broccoli is crisp-tender, about 3 minutes. Wipe the pan clean.
Rub 1 half of each loaf with the remaining 2 tablespoons of butter.Add the bread slices, butter side down, to the pan. Divide the vegetables into breadcrumbs. Place a slice of cheese and a slice of bread on top of each, on top of the butter half.
Cook over medium heat until sandwiches are lightly browned and cheese is melted, 2 to 4 minutes per side. (Cook batches of sandwiches if not all fit in your pan.)
Meanwhile, combine soup with remaining 1 ⅔ cups water in medium saucepan; Cook over medium heat, stirring occasionally, until heated through, about 3 minutes.