• Before starting, preheat oven to 450°F.
• Wash and dry all produce.
• In a large non-stick pan, heat 1/2 tbsp (1 tbsp) oil over medium.
• While the pan heats, using a strainer, rinse leeks to wash away any hidden dirt.
• When the pan is hot, add leeks. Cook for 3-4 min, stirring often, until tender. 
• Add 1 tsp (2 tsp) sugar, half the vinegar and 2 tbsp (4 tbsp) water. Season with salt. Cook for 2-3 min, stirring often, until leeks are dark golden and water is absorbed. 
• Remove from heat. Transfer to a plate.
• Carefully wipe the pan clean.

• Meanwhile, finely chop parsley.
• Halve bocconcini.
• Halve tomatoes.
• Pat chicken dry with paper towels. Season with salt and pepper. Arrange on an unlined baking sheet. Drizzle 1 tbsp (2 tbsp) oil over top. Roast in the middle of the oven for 18-22 min, until golden and cooked through.**

• Reheat the same pan (from step 1) over medium. 
• When hot, add pine nuts to the dry pan. Toast for 2-3 min, stirring often, until golden. (TIP: Keep your eye on them so they don't burn.) 
• Transfer to a plate.
  

• To the same pan, add 1/2 tbsp (1 tbsp) oil, then half the spinach. Stir for 30 sec, until wilted. Season with salt and pepper.
• Remove from heat.

• On a parchment-lined baking sheet, arrange flatbreads. (NOTE: For 4 servings, use 2 parchment-lined baking sheets.) 
• Spread pesto over flatbreads.
• Thinly slice chicken.
• Top with wilted spinach, chicken, caramelized leeks and bocconcini-tomato mixture, then sprinkle Parmesan over top.
• Bake flatbreads in the middle of the oven for 7-8 min, until golden and bocconcini has melted. (NOTE: For 4 servings, bake flatbreads in the middle and top of the oven, rotating sheets halfway through.)

• In a large bowl, whisk together remaining vinegar, 1/4 tsp (1/2 tsp) sugar and 1 tbsp (2 tbsp) oil. Season with salt and pepper.
• Add remaining spinach and remaining tomatoes, then toss to coat.
• Garnish flatbreads with remaining parsley.
• Cut flatbreads into quarters.
• Divide flatbreads and salad between plates.
• Sprinkle pine nuts over salad. Sprinkle chili flakes over flatbreads, if you like.

If you've opted to add chicken breast, pat dry with paper towels. Season with salt and pepper. Arrange on an unlined baking sheet. Drizzle 1 tbsp (2 tbsp) oil over top. Roast in the middle of the oven for 18-22 min, until golden and cooked through.**

Thinly slice chicken. Top flatbreads with chicken.