Preheat oven to 425ºF.

Toss the broccoli and olive oil on a sheet pan and sprinkle with salt and pepper. Roast the broccoli for about 20 minutes, stirring halfway through cooking time, or until tender and beginning to brown. Set aside.

While the broccoli is roasting, start the pasta. Cook the pappardelle in a large pot of boiling salted water, stirring occasionally, until al dente (the pasta will finish cooking in the sauce, so don't overcook it!). Drain, reserving 1 cup of the pasta cooking liquid.

When the pasta's halfway done cooking, start the sauce. Combine the cream and lemon zest in a large pot over medium heat, whisking often, for about 2 minutes, or until the mixture comes to a simmer. Reduce heat to medium-low. Whisk in the butter 1 tablespoon at a time until the sauce is creamy and emulsified.

Add 3/4 cup of the pasta cooking liquid to the cream sauce and return to medium heat. Add the pappardelle to the sauce; cook, tossing often and adding Parmesan little by little, until the cheese is melted and the sauce is creamy, about 3 minutes. (Add remaining pasta water one tablespoon at a time to thin it out, if needed.)

Stir in the lemon juice and roasted broccoli; season with salt and pepper, if needed. Divide onto plates and serve.