Start by boiling a large pot of salted water and cook the bucatini until al dente. Make sure not to overcook, as the pasta will finish in the sauce later. Reserve a cup of pasta water before draining for later use.
While the pasta cooks, chop the asparagus into bite-sized pieces and prepare the peas. Quickly blanch or sauté them so they stay vibrant and slightly crisp. This step ensures the vegetables retain both flavor and texture.
Heat butter and olive oil in a skillet over medium heat, then add minced garlic. Let it cook gently until fragrant, being careful not to burn it. This creates a flavorful base that defines the entire dish.
Pour in the vegetable broth and heavy cream, stirring well to combine. Allow the mixture to simmer until it thickens slightly and becomes smooth. This is where the rich, creamy texture starts to develop.
Stir in freshly grated parmesan cheese, letting it melt completely into the sauce. Add salt, pepper, and red pepper flakes to taste. The sauce should be creamy, slightly thick, and full of flavor.
Add the cooked pasta, asparagus, and peas directly into the sauce. Toss everything together so the pasta absorbs the creamy mixture. Use reserved pasta water if needed to loosen the sauce.
Squeeze in fresh lemon juice and sprinkle chopped herbs on top. This final touch brightens the dish and balances the richness. Serve immediately for the best taste and texture.