Preheat your oven to 350°F (175°C). Grease and flour a 9-inch round cake pan.
In a large mixing bowl, combine the flour, granulated sugar, baking powder, and salt.
Add the softened butter, egg, vanilla extract, and milk to the dry ingredients. Mix until just combined and smooth.
Fold in the chopped cranberries and pecans gently until evenly distributed.
Pour the batter into the prepared cake pan, smoothing the top.
In a small bowl, mix the brown sugar and cinnamon together. Sprinkle this mixture evenly over the top of the batter.
Bake in the preheated oven for 35-40 minutes, or until a toothpick inserted into the center comes out clean.
Allow the cake to cool in the pan for 10 minutes before transferring it to a wire rack to cool completely.