Gooey Chocolate Chip Sandwich Bars

Name: Gooey Chocolate Chip Sandwich Bars
Ingredients: 1 tsp baking powder; 1 tsp baking soda; 1 tsp kosher salt; 1 cup light brown sugar; ½ cup granulated sugar; 1 large egg, at room temperature; 1 large egg yolk, at room temperature; 1 tbsp pure vanilla extract, plus 2 tsp pure vanilla extract; 2 cups all-purpose flour; 1 cup old-fashioned rolled oats; 1½ cups dried cranberries; 3 cups semisweet chocolate chips, divided; 2½ sticks unsalted butter (10 oz), at room temperature; 1 can (14 oz) sweetened condensed milk