Peel and dice the carrots into rounds, about ½ inch thick. Dice the zucchini into rounds, about ½ inch thick thick. Scatter on a baking sheet lined with parchment paper. Drizzle on 1 tablespoon of olive oil, and sprinkle on the dried thyme, rosemary and sweet paprika. Toss to coat the veggies in the oil, herbs and spice. Roast at 390F / 200C for 25 minutes, or until the carrots are fork tender.
While the carrots are in the oven, cook the pasta according to package instructions in salted water. Reserve half a cup of the pasta water. Drain the pasta.
Drizzle olive oil in your skillet and cook the diced onion for 4-5 minutes, then add in the garlic and cook for another minute until fragrant.
Spoon the roasted carrots and zucchini into your blender, along with the cooked onion. Pour in the vegetable stock and spoon in the mascarpone cheese. Add a pinch of salt (and black pepper, if using). Blend until smooth.
Pour the carrot sauce into the skillet, and tip in the pasta. On a low heat, stir the sauce to coat the pasta, adding the reserved pasta water in a tablespoon at a time until you have the sauce consistency you enjoy. Season again, if required, and heat until warmed through.