Fill a medium pot 3/4 of the way up with salted water; cover and heat to boiling on high. Wash and dry the fresh produce. Pick the rosemary leaves off the stems. Roughly chop the walnuts. Peel and thinly slice the shallot. Peel and roughly chop 2 cloves of garlic. Separate the kale leaves from the stems; discard the stems, then roughly chop the leaves. 

Add the pasta to the pot of  boiling water. Cook 10 to  12 minutes, or until al dente (still slightly firm to the bite). Reserving ½ cup of the pasta cooking water, drain thoroughly. 

Meanwhile, in a large pan, heat a thin layer of oil on medium-high. Once the oil is hot enough that a rosemary leaf sizzles  immediately when added, add the rosemary leaves and chopped walnuts. Season with salt and pepper. Cook, stirring frequently, 2 to 3 minutes, or until fragrant and the rosemary is crispy. Transfer to a paper towel-lined plate and immediately season with salt. Wipe out the pan.

In the same pan, heat 2 teaspoons of olive oil on medium-high until hot. Add the sliced shallot and chopped garlic; season with salt and pepper. Cook, stirring constantly, 1 to 2 minutes, or until lightly browned and slightly softened. Add the chopped kale and as much of the red pepper flakes as you’d like, depending on how spicy you’d like the dish to be; season with salt and pepper. Cook, stirring frequently, 2 to 3 minutes, or until the kale is slightly wilted. Add the verjus (carefully, as the liquid may splatter) and 1/4 cup of  water. Cook, stirring frequently, 2 to 3 minutes, or until the kale is wilted and the liquid has cooked off. Turn off the heat. Taste, then season with salt and pepper if desired.

To the pan of finished kale, add the cooked pasta, butter, and half the reserved pasta cooking water. Cook on medium-high, stirring constantly, 1 to 2 minutes, or until the pasta is coated (if necessary, gradually add the remaining cooking water to ensure the pasta is thoroughly coated). Turn off the heat and stir in the mascarpone until combined. Taste, then season with salt and pepper if desired. Serve the finished pasta garnished with the fried rosemary and walnuts and parmesan. Enjoy!