Lemon-Ricotta Pancakes

INGREDIENTS

• 2 cups mixed fresh berries
• 2 tablespoons finely grated lemon zest
• 4 large eggs, separated
• Melted unsalted butter for brushing
• 1/2 teaspoon kosher salt
• 2 tablespoons fresh lemon juice
• 1 1/2 cups whole milk
• 2 tablespoons baking powder
• 1/3 cup plus 4 tablespoons sugar, divided
• 1/2 cup chestnut flour
• 2 cups ricotta
• 1 1/2 cups all-purpose flour