Wash and peel the asparagus, cut off the ends. Cook with salt, sugar and 1 tablespoon butter until al dente. Preheat the oven to 220 ° C.
Put the asparagus in a buttered ovenproof dish. Drain the mozzarella and cut into 16 slices, season with pepper and cover each with a leaf of basil. Halve the ham slices and wrap them around the mozzarella slices. Place ham and mozzarella parcels on top of the asparagus in the baking dish. Gratinate the casserole in the oven on the middle rack for about 15 minutes until golden brown.
In the meantime, melt the butter in a small saucepan. Chop the rest of the basil and add. Brown the sauce, season with pepper and salt, then season with white wine. Pour the sauce over the casserole.