Preheat the oven to 350°F (175°C) and prepare a 9-inch cake pan by greasing it with butter and lining the bottom with parchment paper.

In a large bowl, cream the softened butter and granulated sugar using an electric mixer until light and fluffy, about 3–5 minutes.

Add the eggs one at a time, mixing well after each addition to maintain emulsion.

Stir in the pure vanilla extract until fully blended into the batter.

In a separate bowl, whisk together the flour, baking powder, and salt. Gradually add this dry mixture to the wet batter while mixing on low speed.

Pour in the whole milk or heavy cream and mix gently until the batter is smooth and uniform.

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

Bake in the preheated oven for 40–50 minutes, checking for doneness with a toothpick around the 40-minute mark.

Let the cake cool in the pan for about 10–15 minutes before inverting onto a wire rack to cool completely.