Comforting Creamy Tuna with Basil Pesto and Pasta

Ingredients

• 8 oz pasta such as penne, fusilli, spaghetti, or fettucine
• 2 tablespoons olive oil
• 1/2 small onion, finely chopped
• 2 cloves garlic, minced
• 5 oz canned tuna in olive oil, drained and flaked
• 1/2 cup basil pesto
• 1/2 cup heavy cream
• 1/4 cup grated Parmesan cheese (optional)
• 1 teaspoon lemon zest (optional)
• Salt
• pepper
• 1/4 cup reserved pasta water if needed
• 1 cup baby spinach
• 1/2 cup cherry tomatoes, halved
• 1/4 teaspoon red pepper flakes