Making French Butter Cake is straightforward if you follow these simple steps:

1. Preheat Oven: Set your oven to 350°F (175°C). Grease and flour a 9-inch round cake pan.
2. Cream Butter and Sugar: In a large mixing bowl, beat the softened butter and granulated sugar together until light and fluffy.
3. Add Eggs: Mix in the eggs one at a time, ensuring each is fully incorporated before adding the next.
4. Add Vanilla: Stir in the vanilla extract to enhance the flavor.
5. Combine Dry Ingredients: In another bowl, whisk together flour, baking powder, and salt.
6. Alternate Mixing: Gradually add the dry ingredients to the butter mixture, alternating with the milk. Start and end with the flour mixture, mixing until just combined.
7. Add Optional Zest: If using, fold in the zest at this point for a citrusy note.
8. Pour Batter: Pour the batter into the prepared cake pan, smoothing the top with a spatula.
9. Bake: Place in the oven and bake for 45-50 minutes, or until a toothpick inserted into the center comes out clean.
10. Cool: After baking, allow the cake to cool in the pan for about 15 minutes. Then transfer to a wire rack to cool completely.
11. Serve: Once cool, you may dust with powdered sugar or serve with your favorite toppings.

Following these steps will guide you in creating an incredible French Butter Cake that is sure to impress!