Irresistible Ube Cookies with White Chocolate Chunks - Yummy Gusto

Ingredients

• 3 cups plain flour
• 1 tbsp cornstarch
• 3 tsp baking powder
• 1 tsp salt
• 1 cup softened unsalted butter
• ½ cup white sugar
• 1¼ cup brown sugar
• 15 oz ube jam (roughly 2 cups), softened
• 1 large egg, not cold
• 1 large egg yolk, not cold
• 2 tbsp ube flavoring
• 1 cup white chocolate chunks, plus extra for decoration