Meanwhile, make the sauce: Heat olive oil, 2 turns of the pan, over medium heat. Melt butter into oil and stir in garlic and onions, thyme, salt and pepper, and partially cover. Let sweat 5 minutes, stirring frequently, to soften. Add stock and stir in purée and tomatoes, breaking up tomatoes with potato masher. Stir in torn basil; simmer 45 minutes adding the meatballs after 15 minutes.
Mix together the ricotta with eggs, nutmeg and half of the Parm cheese. Finely chop the ham.
Reduce oven temp to 375ºF.
Build lasagna in 9x13” pan: first some sauce then 3 ribbons of lasagna noodles, half the ricotta, 1/3 of the mozzarella, half the ham, another layer of pasta, a layer of half the meatballs and some of the sauce, then sprinkle with some Parm. Repeat the layers again and top with last of the red sauce and the remaining mozzarella and Parm cheese.
Bake lasagna covered with foil on baking sheet for 45-50 minutes. Remove foil and bake to brown, 10-15 minutes more. Let stand at room temp 15-20 minutes before cutting.