Cook the rigatoni pasta as per the instructions on the packaging.
While the rigatoni cooks, heat 1/4 cup of olive oil in a large skillet or saucepan over medium heat. Once the oil is shimmering, add the garlic. Stirring often, let the garlic simmer for about a minute, until aromatic. Scoop 1 cup of pasta water from your boiling rigatoni and add it to the skillet, then add the spinach. Keep tossing and stirring it around in the hot pan until all of it has wilted down, about 5-7 minutes. Finally, stir in the chili flakes, salt, and pepper. Remove the skillet from the heat and set aside.
Heat a small dry saucepan over medium heat. Once hot, dump the Italian breadcrumbs into the pan and let them toast for about 3 minutes or until golden brown and aromatic. Be sure to shake the pan often to prevent burning.
When the rigatoni is done, drain it and transfer it to the skillet with the garlic and spinach. Add half of the toasted breadcrumbs and give it a good toss. Add the parmesan and the rest of the breadcrumbs, and stir again. Adding the toasted breadcrumbs in two segments prevents clumping and gives better coverage.
Taste, and season with salt and pepper to your taste. Add extra chili flakes if you're up to it!