Preheat your oven to 425°F (220°C).
In a baking tray, place the sliced onions. Sprinkle with salt, pepper, and paprika powder. Drizzle with 2 tablespoons of olive oil.
Mix everything well to ensure the onions are evenly coated.
Place the whole garlic head, with the top sliced off, in the middle of the tray. Drizzle with 1 tablespoon of olive oil.
Pop the tray in the oven and bake for 1 hour. The onions should be caramelized and golden brown, and the garlic should be soft.
After baking, remove the tray from the oven. Squeeze the roasted garlic out of its skin and add it to the tray.
Squeeze the lemon juice over the mixture.
Add the spinach and fresh parsley. Stir well to combine.
Pour in the vegan cream and 2-3 ladles of pasta water. Mix until the sauce is smooth and well incorporated.
Add the cooked pasta to the tray. If the sauce seems too thick, add more pasta water as needed.
Stir everything together until the pasta is well coated with the sauce.
Taste and adjust the seasoning with salt and pepper if necessary.
Serve the pasta hot, garnished with extra parsley if desired.