Cook pasta according to package directions for al dente, in salted water. Drain, but reserve 1/2 cup pasta cooking water.
Meanwhile, in a large pan on medium heat, add onions, oil, 1 tsp of kosher salt, and pepper. Stir, cook for 5 min. Add garlic, cook another min. Add garlic powder and vegetable broth, let gently simmer for 2 min.
Add broccoli florets and peas, stir and cook covered for 2 to 3 min. Remove lid and cook more time if broccoli is not yet fork tender. Add pasta and remaining ingredients, stir and add the last 1/2 tsp kosher salt if desired. Add in some of the reserved pasta cooking water to thin the sauce if desired.
Serve and top with red chili flakes and black pepper.