Preheat oven to 350ºF. Grease and lightly flour a 9x5” loaf pan
In a medium bowl sift together flour, 1 cup of sugar, baking powder, and salt.
In a large bowl combine 3 tablespoons of butter and the milk. Add flour mixture and mix well. Add cranberries. Pour into prepared pan and bake for 1 hour. Let cool on wire rack.
On medium heat, in the top of a double boiler, over simmering water melt ½ cup of butter. Stir in 1 cup sugar, the half and half and the vanilla. Reduce the heat, bring to a boil and simmer for 15-20 minutes until slightly thickened.
Spoon the sauce onto dessert plates and place a slice of cake on the sauce to serve.