Step 1: Preheat your oven to 350°F (175°C). Grease and flour a 9x13 inch baking pan or a 10-12 cup Bundt pan.
Step 2: In a large mixing bowl, cream together the softened butter and granulated sugar with an electric mixer until light and fluffy, about 3-5 minutes.
Step 3: Add 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 sifted flour, baking powder, baking soda, and salt.
Step 5: Gradually add the dry ingredients to the wet ingredients, alternating with the buttermilk, beginning and ending with the dry ingredients. Mix on low speed until just combined. Do not overmix.
Step 6: Pour the batter into your prepared baking pan, spreading evenly.
Step 7: Bake for 30-40 minutes for a 9x13 pan, or 50-60 minutes for a Bundt pan, or until a wooden skewer inserted into the center comes out clean.
Step 8: Let the cake cool in the pan for 10-15 minutes before inverting it onto a wire rack to cool completely.
Step 9: While the cake cools, prepare the glaze (if using). Whisk together powdered sugar, milk, and vanilla extract until smooth. Drizzle over the cooled cake.