1Preheat the oven to 350F.
2In a large pot of boiling salted water, cook the manicotti noodles according to package directions. Set aside on a baking sheet until they're cool enough to handle.
3In a large skillet, cook the bacon until crisp; transfer to a medium bowl with a slotted spoon. Add the onion to the drippings in the skillet (remove some with a spoon if there's a lot) and cook for 4-5 minutes, or until soft and turning golden. Add the spinach, chard or kale to the pan and cook for a minute or two, until it wilts. (If you're using kale, add a splash of the pasta cooking water to help it along, and loosen any browned bits from the bottom of the pan.) Transfer to the bowl with the bacon. Once it cools down, add the ricotta, half a cup of mozzarella and half the Parmesan, and some salt and pepper, and stir to combine.
4Add a glug of olive oil to the skillet (don't bother washing it out), warm it over medium-high heat and cook the garlic for a minute, just until fragrant. Add the crushed tomatoes to the pan and stir to heat through.
5Spread a large spoonful of the tomatoes over the bottom of a 9x13-inch (or similarly-sized) baking dish. Stuff the manicotti with the ricotta mixture using a small spoon and your fingers, laying them in the pan as you go. Spread the remaining tomatoes overtop and sprinkle with the remaining mozzarella and Parmesan. Bake for 45 minutes, or until bubbly and golden.