Kale Pesto Pasta

Why This Kale Pesto Pasta Works

As the pasta boils, starch from the noodles moves into the water and lightly coats the outside of each piece. That thin starchy layer is what lets the kale pesto cling to the pasta instead of sliding off. When a little of that pasta water is saved and stirred back in later, it loosens the pesto at first, then the starch in the water thickens it again so it sticks in all the curves and gaps of the noodles.

Inside the food processor, the kale, walnuts, and Parmesan break down into tiny bits. As the olive oil and lemon juice go in, the oil wraps around those small pieces and they start to hold together like a smooth paste instead of a dry crumble. Once the warm pasta is tossed with the pesto, the heat softens the cheese and garlic a bit, so the sauce spreads more easily and coats everything in an even layer.

Mistakes To Avoid

Letting the pasta cook past al dente makes it too soft to stand up to the thick pesto. Once the pesto and a bit of pasta water go on, the noodles swell even more and turn mushy instead of pleasantly chewy.

Packing the food processor with wet kale leaves often leads to a watery pesto. The extra moisture thins the sauce, so it slides off the pasta and pools at the bottom of the bowl instead of coating each piece.

Skipping the step of slowly streaming in the olive oil causes the pesto to stay chunky and uneven. Big bits of kale and walnuts remain, so the sauce clumps on some noodles while other parts of the pasta stay bare and dry.

Leaving out the pasta water or adding a lot all at once can throw off the texture. Without enough, the pesto stays pasty and sticks in blobs; with too much, it turns soupy and runs off the pasta instead of clinging to it.