Chop all the vegetables and combine in a slow cooker. Add the chicken broth. Whisk together the light cream and flour with a fork, pressing the back of the fork against the measuring cup to break up the little crumbs of dry flour. Add cream/flour mixture to the broccoli mixture and stir. Add salt, nutmeg, and black pepper, stir again. Add cheeses and stir once more.
Combine the panko breadcrumbs and melted butter in a bowl, add salt and pepper to taste, mix well. Spoon the breadcrumb mixture over the top of the broccoli mixture.
Set the slow cooker to high and cook for 3-4 hours, or on low for 6-8 hours. Turn slow cooker off and allow to sit for about 10 minutes before transferring to a serving dish.