Place spinach in a microwave safe bowl with a splash of water. Cover and microwave until the spinach has wilted, about 5 minutes. Drain and allow to cool.
In a large bowl mix together beef, pork, eggs, bread crumbs and Romano cheese. Season with salt and pepper. Divide into two equal portions and roll each into balls.
Place a 40cm long piece of cling wrap on your work surface and lightly sprinkle with flour. Place one of the balls onto the cling wrap and pat into a thin, 20cm by 25cm rectangle. Cover evenly with half of the spinach and 3 slices of prosciutto, then shingle three slices of provolone running along the edge facing you.
Using the cling wrap to lift the meat roll the loaf, starting from the cheese side, into a firmly packed spiral, peeling away the cling wrap as you go. Make a second loaf with remaining ingredients.
To bake, pour wine into a grill pan bottom. Oil the slotted top with some of the olive oil before placing the loaves on and brushing them with remaining oil. Cover loaves with a sheet of aluminium foil and bake in preheated oven for 40 minutes.
Remove the foil and pour water into the pan. Continue baking for another 35 minutes. Allow to rest 10 minutes before slicing into 3cm thick slices to serve.