Preheat the oven to 350°F (175°C).

In a 9-inch round cake pan, pour melted butter and sprinkle brown sugar evenly over it.

Spread the cranberries over the sugar and butter mixture.

In a medium bowl, whisk together the flour, baking powder, and salt.

In a large bowl, cream together butter and sugar until light and fluffy.

Add eggs one at a time, beating well after each addition, then stir in vanilla.

Gradually add the flour mixture to the creamed mixture alternately with milk, starting and ending with flour mixture.

Pour batter over the cranberries in the cake pan and spread evenly.

Bake in the preheated oven for 45 minutes, or until a toothpick inserted into the center comes out clean.

Let the cake cool in the pan for 10 minutes, then carefully invert onto a serving plate.