Preheat the oven to 350°F (175°C). Grease a 9-inch round cake pan and line the bottom with parchment.

In a large bowl, beat the softened butter and sugar with an electric mixer on medium-high for about 3–5 minutes until pale and fluffy.

Add the eggs one at a time, beating well after each addition. Mix in the vanilla extract.

In a separate bowl, whisk together the flour, baking powder, and salt.

Add the dry ingredients to the butter mixture in three portions, alternating with the milk: flour, milk, flour, milk, flour. Stir each addition until just combined.

Pour the batter into the prepared pan and smooth the top with a spatula.

Bake for 35–40 minutes, until the top is golden and a toothpick inserted into the center comes out clean.

Cool the cake in the pan for 10 minutes, then turn it out onto a wire rack to cool completely before slicing.