Prep and roast the beets: Heat the oven to 400°F (200°C). Wrap the beets in foil with 1 tablespoon olive oil and a pinch of salt.
Roast on a baking sheet for 45–60 minutes, until a knife slides in easily.
Cool and peel: Let the beets cool until you can handle them. Rub off the skins with a paper towel or your hands. Chop into chunks.
Cook the pasta: Bring a large pot of salted water to a boil.
Cook the pasta until al dente. Reserve 1 to 1.5 cups of pasta water before draining.
Bloom the garlic: In a skillet over medium heat, add 1 tablespoon olive oil. Gently cook the garlic for 1–2 minutes until fragrant and just golden, not browned.
Blend the sauce: In a blender, combine roasted beets, garlic, cream, lemon juice, half the lemon zest, a pinch of red pepper flakes, 1/2 teaspoon salt, and a few grinds of pepper.
Blend until completely smooth. Add a splash of pasta water if it’s too thick.
Finish the sauce: Return the skillet to low heat. Add the butter and beet sauce.
Warm gently for 1–2 minutes, stirring. Don’t boil; you want it silky.
Toss with pasta: Add the drained pasta to the skillet with 1/2 cup pasta water. Toss until coated and glossy.
Stir in the Parmesan until melted and smooth. Add more pasta water as needed for a creamy consistency.
Adjust and serve: Taste and adjust with salt, pepper, or more lemon juice. Plate and top with extra Parmesan, remaining lemon zest, herbs, and nuts if using.