Pizza with basil pesto

Ingredients:

• 2 large pizza bases, white or whole wheat
• 4 tbsp. l. + 1 tbsp. olive oil
• 4 medium sweet onions, such as Vidalia, thinly sliced
• 6 tablespoons whole raw walnuts
• 2/3 cup grated Parmesan cheese, plus extra for sprinkling (optional)
• 1/4 cup freshly squeezed lemon juice (from about 1 lemon)
• 4-5 cloves of garlic, crushed
• Sea salt
• 4 cups coarsely chopped fresh basil
• 2 cups loosely packed fresh spinach
• 1 cup finely chopped Kalamata olives
• 1 tbsp balsamic vinegar
• 3 medium tomatoes, thinly sliced

Preparation:

1. Preheat oven to 220°C.
2. In a medium saucepan, heat 2 tablespoons olive oil over medium heat until shimmering, about 2 minutes, then add the onion. Cook over low heat, stirring occasionally, until the onion is golden brown and caramelized, 20 to 30 minutes.
3. Meanwhile, combine the walnuts and 1 cup olive oil in a food processor and process until smooth, about 1 minute. Add the Parmesan, lemon juice, garlic, and 1 teaspoon sea salt and process until smooth, about 1 minute. Add 3 3/4 cups chopped basil, reserving the remaining 1/4 cup for sprinkling on the pizza. Add the spinach and process until smooth, about 1 minute.
4. In a medium skillet, heat the remaining 2 tablespoons olive oil over medium heat until shimmering, about 2 minutes. Add the olives and sauté for 5 minutes. Remove from heat, then stir in the balsamic vinegar and a pinch of sea salt to taste.
5. For assemblyPlace the pizza crusts on two baking sheets or large round pizza pans. Spread the pesto sauce on top, leaving a 0.5 cm border. Top with the caramelized onions, tomatoes, reserved basil, and olive oil mixture. Sprinkle with a little grated Parmesan cheese, if desired. Bake until the crusts are golden brown, 8 to 10 minutes.