Step 1

Cook the pasta according to package instructions in a large pot of heavily salted water. (It should be so salty it tastes like the ocean.)

Step 2

In a large skillet, heat the olive oil and 2 TBSP of the butter over medium heat. Add the onion and a sprinkle of kosher salt, to taste, stirring to coat. Cook the onion, stirring occasionally, until it softens and begins to become translucent, about 3 minutes. Stir in the garlic and cook until fragrant, about 1 minute more. Stir in the asparagus, red pepper flakes, and a pinch more kosher salt. Cook until asparagus pieces are tender, about 3 minutes more.

Step 3

While the asparagus is cooking, drain the pasta, reserving 1 cup of the pasta water. Once the asparagus is tender, add the cooked pasta to the skillet.

Step 4

Add the pesto and 4 – 6 more TBSP of butter (or to your preference) to the skillet, tossing everything until pesto has coated the pasta and butter is melted. Add a splash of the reserved pasta water to thin the sauce, if desired.

Step 5

Garnish the pasta with fresh lemon zest, parmesan cheese, and toasted breadcrumbs to serve.