Preheat your oven to 350°F (175°C) and grease a 9x13 inch baking pan.

In a large mixing bowl, cream the softened butter and sugar together on medium speed for 2-3 minutes until light and fluffy.

Add the eggs one at a time, beating well after each addition, then pour in the vanilla extract and mix until smooth.

In a separate bowl, whisk together the flour, baking powder, and salt. Gradually add to the wet ingredients, mixing gently.

Fold in the cranberries carefully to distribute them evenly throughout the batter.

Pour the batter into the prepared pan and spread it evenly using a spatula.

Bake for 30-35 minutes until the edges are golden brown and a toothpick inserted in the center comes out clean.

Allow to cool completely on a wire rack before slicing into squares.