Preheat the oven to 425 degrees(F).
Spread the broccoli florets onto a large sheet pan. Drizzle the broccoli with the olive oil and sprinkle with the blackened seasoning. Toss to coat the broccoli in the oil and seasoning.
Roast in the oven for 15 minutes, take the broccoli out of the oven, toss the broccoli, and roast for another 7-10 minutes or until the broccoli has a nice brown char on the edges.
While the broccoli is in the oven, cook the pasta according to package directions, then drain when it is al dente.
I like to toss the pasta with a drizzle of olive oil so it does not stick together while I make the sauce. Set aside.
Using the pot you cooked the pasta in, heat the vegan butter and olive oil on medium. Once the butter has melted, add the garlic and saute for 2-3 minutes.
Sprinkle the flour into the pot and whisk it with the butter and oil until you have formed a paste. Let simmer for a minute.
Pour in the vegan cream and broth, whisk to combine everything, making sure that there are no lumps of flour remaining.
Add the blackened seasoning, the zest and juice of the lemon(about 2 teaspoons of juice) and whisk. Let the sauce simmer for a few minutes on medium-low, until the sauce thickens
Add the vegan parmesan and whisk the sauce until the cheese has melted as much as it can.
Taste the sauce and adjust the seasoning, adding salt, pepper, and/or more lemon if needed.
Pour the pasta and broccoli into the pot with the sauce and toss to combine everything. Serve!