Preheat oven to 350° F. Lightly spray a 9" x 13" baking pan with nonstick spray and set aside.
In a large bowl, sift together the flour, sugar, baking powder, and salt.
Add cranberries, milk, and melted butter to dry ingredients and mix well.
Pour batter into prepared pan and bake for about 45 minutes, until the top is golden and a toothpick inserted in the cake comes out clean. Remove pan to a wire rack to cool.
For the Buttercream Sauce
Melt butter in a medium sauce pan over medium heat.
Add sugar and cream, and stir to combine. Bring to a boil and cook for 1 minute. Remove from heat.
To Serve
Place individual pieces of cake onto small plates or dessert bowls. Pour warm butter cream sauce over pieces of cake. Garnish with , if desired.
Nutrition information is automatically calculated by Spoonacular. I am not a nutritionist and cannot guarantee accuracy. If your health depends on nutrition information, please calculate again with your own favorite calculator.