01 -
Preheat the oven to 350°F (175°C). Lightly grease a 13 x 9-inch baking pan.
02 -
In a large mixing bowl, beat softened butter with granulated sugar until the mixture is crumbly. Add the egg and beat until smooth. In a separate bowl, whisk together flour, baking powder, and salt. Alternate adding the dry ingredients and the milk to the butter mixture, beating well after each addition. If desired, chop cranberries coarsely. Gently fold cranberries into the batter.
03 -
Pour the batter into the prepared pan and smooth the surface. Bake for 20–25 minutes, or until a toothpick inserted in the center emerges clean.
04 -
While the cake is baking, combine brown sugar, water, granulated sugar, and butter in a large saucepan. Bring to a boil over medium heat, stirring constantly to dissolve the sugars. Continue to cook, stirring, until the sauce thickens slightly. Remove from heat and stir in vanilla extract.
05 -
Cut the warm cake into squares and serve immediately, spooning the hot sauce generously over each portion.