1. Toast almonds in small skillet over medium heat, stirring frequently, until pale golden and fragrant, 2 to 4 minutes. Cool almonds to room temperature.

2. Process cooled pine nuts, tomatoes, arugula, garlic, pepperoncini, 1 teaspoon salt, zest, lemon juice, and red pepper flakes (if using) in food processor until smooth, about 1 minute. Scrape down sides of bowl with rubber spatula. With machine running, slowly drizzle in oil, about 30 seconds.

3. Meanwhile, bring 4 quarts water to boil in large pot. Add pasta and 1 tablespoon salt and cook until al dente. Reserve 1/2 cup cooking water; drain pasta and transfer back to cooking pot.

4. Add pesto and 1/2 cup Parmesan to cooked pasta, adjusting consistency with reserved pasta cooking water so that pesto coats pasta. Serve immediately, passing Parmesan separately.

Serves 4 to 6