Lemon White Chocolate Chip Cookies

Ingredients

• 1 1/4 cup granulated sugar
• 1 Tbsp. lemon zest (or more for more lemony flavor)
• 3/4 cup unsalted butter, softened
• 3 cups all-purpose flour, spooned and leveled
• 1 tsp. cornstarch
• 1/2 tsp. baking powder
• 1/2 tsp. baking soda
• 1/2 tsp. salt
• 1 large egg, room temperature
• 1/2 cup sour cream, room temperature
• 1 Tbsp. lemon juice, freshly squeezed
• 1 tsp. lemon extract
• 1 tsp. vanilla extract
• 1 cup white chocolate chips, plus more for garnishing the tops
• 1/4 cup granulated sugar
• 2 Tbsp. lemon juice