1) Bring a large pot of cold water to a boil and salt it generously. Cook garlic in olive oil in a large skillet over medium-high heat, stirring occasionally, until golden brown and crispy, about 3 minutes; take care that the garlic doesn't get too brown or it will be bitter. Using a slotted spoon, transfer the garlic chips to a paper towel. Pour off and reserve all but 30ml of oil.
2) Add the onions and red pepper (add a little more if you like things spicy) to the skillet and cook, stirring, until light brown, about 10 minutes. Season with the 2 teaspoons of salt.
3) When the onions are almost done, add the greens to the boiling water and cook, uncovered, just until tender, about 2 minutes. Using tongs, lift the greens from the water, shake off the excess water, add them to the onions, and cook, stirring occasionally, until tender, about 5 minutes.
4) Bring a fresh pot of water to a boil. Salt it generously, add the spaghetti, and cook, stirring occasionally, until al dente, 8 to 10 minutes. Scoop out and reserve about 250ml of the cooking water; drain the pasta. Transfer the pasta to a serving bowl and toss with the cheese. Add the greens and some of the reserved pasta water and toss, adding more water as necessary to keep the pasta from clumping. Scatter the garlic chips over the top and serve.
Chefs note: Speed-wash your greens like we do here in the Food Network Kitchens: Tear up the leaves, swish them in a big bowl of water, shake them semi-dry, and get cooking.