Bring a large pot of water to a boil for the pasta. Once boiling, add salt and drop the pasta. Cook to al dente. Reserve 3/4 cup of the starchy cooking liquid just before draining.
While the pasta cooks, place tarragon, basil and mint in a food processor. Add the lemon zest and juice, garlic, nuts, fennel, salt, pepper, cheese and about 1/4 cup EVOO. Pulse into a paste and transfer to a serving bowl.
Place remaining 2 tablespoons EVOO in a skillet over medium to medium-high heat. Add zucchini and season with salt and pepper. Cook until light golden in color, 8-10 minutes. Transfer to the bowl with the pesto sauce.
Add starchy cooking water to bowl along with pasta and zucchini flowers, if using. Toss to coat pasta and combine the sauce.