Begin boiling water in a pot to cook pasta according to package directions.
In a separate large skillet/saucepan heat 2 tablespoons of avocado or cooking oil over slightly above medium heat. Once pan is hot enough that a drop of water sizzles, add onion. Generously season with salt and pepper and stir. Cook for 5-6 minutes until onions are beginning to become tender and translucent.
While onion is cooking, whisk together water, chicken boulion granules, 1/4 cup lemon juice, whipping cream, cornstarch, garlic powder, 1/4 teaspoon pepper, and 1/4 teaspoon salt. Set aside.
To the saucepan, add mushrooms, basil, oregano, and thyme and cook for 5 minutes more, stirring occasionally to avoid burning.
Add pasta to boiling water at this point. Cook pasta for 10 minutes before draining. As pasta is cooking, continue cooking vegetables.
While mushrooms are cooking, cut zucchini and yellow squash in half lengthwise. Cut halves into 1/2" thick pieces. Add zucchini and squash to sauce pan and cook until crisp tender, about 5 minutes more. Add chopped kale and capers and cook an additional 2 minutes.
Pour liquid mixture into saucepan and increase heat to medium high. Bring mixture to a boil and stir until slightly thickened, about 3 minutes.
Drain pasta and add cooked pasta to saucepan. Stir to coat all pasta with sauce. Season with additional salt and pepper, if needed. Add extra lemon juice if desired. Serve immediately.