Cook collards in water and chicken broth for 20 minutes. Drain well and set aside. Halve croissants and cut each half into 5 pieces. Place croissant pieces in a lightly greased 10-inch deep casserole dish. Combine collards with ham and cheese. Top croissant pieces with collard mixture. Whisk egg, half and half, mustard, honey, salt, pepper, and nutmeg together. Pour over collard mixture, pressing croissants down to submerge into egg mixture. Cover tightly and chill for 8 – 24 hours. Heat oven to 325 F. Bake, covered, for 35 minutes. Uncover and bake for 25 – 30 minutes or until browned and set. Let stand 10 minutes before serving.