Add the garlic, onion and the remaining 1 tablespoon of olive oil to the casserole and cook over moderate heat until softened. Add the carrots and spices and cook, stirring, until fragrant, about 2 minutes. Stir in the flour and add the lamb and water. Bring to a boil, stirring to scrape up any browned bits from the bottom of the casserole. Reduce the heat to low and simmer uncovered, stirring occasionally, until the lamb is tender and the sauce is thickened, about 1 1/2 hours. Raise the heat to moderately high and stir in the spinach until wilted. Season with salt and pepper. Spoon the lamb stew into 4 shallow 2 1/2-cup glass or ceramic baking dishes.