Preheat your oven to 350°F (175°C). Lightly grease an 8x8 inch baking pan or line it with parchment paper.
In a medium bowl, whisk together the all-purpose flour, baking powder, and salt. Set aside.
In a large bowl, beat the softened butter, brown sugar, and granulated sugar with an electric mixer or whisk until light and fluffy, about 3 to 4 minutes.
Beat in the eggs one at a time until fully incorporated, then stir in the vanilla extract until smooth and glossy.
Gradually add the dry flour mixture to the wet ingredients, mixing gently until just combined. Avoid overmixing.
Gently fold in the dried cranberries and white chocolate chips using a spatula to distribute evenly.
Spread the batter evenly into the prepared pan. Bake for 25–30 minutes, or until edges are golden and a toothpick comes out mostly clean with moist crumbs. Cool completely on a rack.
Beat the softened cream cheese until smooth. Add powdered sugar, lemon juice, and vanilla extract, mixing until creamy and well combined.
Spread the cream cheese frosting evenly over the cooled bars. Optionally, sprinkle extra dried cranberries or white chocolate chips on top. Chill for at least 30 minutes before slicing.
