Step 1: Preheat your oven to 350°F (175°C). Butter and flour a 9-inch round cake pan; tap out any excess flour.
Step 2: In a large bowl, cream together the 1 cup unsalted butter and 1 cup of the granulated sugar until light and fluffy, about 3-5 minutes.
Step 3: Add the eggs one at a time, beating well after each addition until fully incorporated. Stir in the vanilla extract.
Step 4: In a separate medium bowl, whisk together the cake flour and baking powder.
Step 5: Gradually add the dry ingredients to the wet ingredients, mixing on low speed until just combined. Be careful not to overmix.
Step 6: Pour the batter into the prepared cake pan and spread evenly.
Step 7: Sprinkle the remaining ¼ cup of granulated sugar evenly over the top of the batter. This will create a delightful sugary crust.
Step 8: Bake for 35-40 minutes, or until a wooden skewer inserted into the center comes out clean and the top is golden brown. If the top browns too quickly, you can tent it loosely with foil.
Step 9: Let the cake cool in the pan on a wire rack for 10-15 minutes before inverting it onto the rack to cool completely. Slice and serve warm or at room temperature.