Winter Citrus Bars

Ingredients

• ***For the crust and the topping:***
• 7 tablespoons unsalted butter, softened
• 3/4 cup light or dark brown sugar, packed
• 1 teaspoon pure vanilla extract
• 1 cup all-purpose flour, spooned and leveled
• 1 teaspoon baking powder
• 1/4 teaspoon salt
• 1 cup old-fashioned whole oats or quick oats
• ***For the lemon filling:***
• 1 (14-ounce) can sweetened condensed milk, full-fat
• 6 tablespoons lemon juice
• 1 tablespoon lemon zest