Defrost the spinach in the microwave, wring dry and separate.
Heat the EVOO in a pan over medium-high heat. Pat the meat dry, and then add to the pan and lightly brown while you crumble. Sprinkle with salt and pepper. . Add the onions and garlic and cook 10 minutes more, stirring occasionally. Deglaze the pan with the wine, stir and add 2 cups tomato puree, followed by the spinach. Stir, reduce heat to a low simmer and simmer 15 to 20 minutes.
Pour the remaining 2 cups tomato puree into a casserole.
Melt the butter in saucepot over medium to medium-high heat. Whisk in the flour for 1 minute. Then add the milk, bring to a bubble, season with salt, pepper and nutmeg, and cook until it's thick enough to coat a spoon. Stir in the soft cheese.
Working over the casserole dish, fill the manicotti with the meat using a spoon. Top the manicotti with the white sauce and Parmesan. Cover with parchment and foil and cool or bake off. Bake, covered, at 375 degrees F for 40 minutes from fresh, or bake 1 hour from cold to heat through and cook the pasta. Then uncover and bake until brown and bubbly, about 20 minutes more.