Preheat Oven: Preheat your oven to 350°F (175°C) and grease and flour a 9-inch round or square cake pan.
Prepare the Batter: In a large mixing bowl, cream the softened butter and sugar together until light and fluffy. Add in the eggs one at a time, mixing well after each addition. Stir in the vanilla extract.
Combine Dry Ingredients: In another bowl, whisk together the flour, baking powder, salt, and cinnamon. Gradually add this mixture to the butter mixture, alternating with the milk, until just combined.
Prepare the Topping: In a small bowl, mix together the brown sugar, cinnamon, and chopped nuts (if using).
Assemble the Cake: Pour the batter into the prepared pan and spread it evenly. Sprinkle the topping mixture over the top.
Bake: Bake the cake for 30-35 minutes, or until a toothpick inserted in the center comes out clean.
Cool and Serve: Let the cake cool in the pan for 10 minutes, then transfer to a wire rack to cool completely. Serve warm or at room temperature.