Preheat the oven to 350°F (175°C). Grease and flour two 9-inch round cake pans, or line them with parchment paper.

Mix dry ingredients: In a medium bowl, whisk together the flour, baking powder, and salt. Set aside.

Cream butter and sugar: In a large mixing bowl, beat the softened butter and granulated sugar together until light and fluffy, about 3-4 minutes.

Add eggs and vanilla: Beat in the eggs, one at a time, ensuring each is fully incorporated before adding the next. Stir in the vanilla extract.

Alternate adding dry ingredients and milk: Gradually add the dry ingredients in three parts, alternating with the milk. Start and end with the dry ingredients, mixing just until combined after each addition.

Bake: Divide the batter evenly between the prepared cake pans. Bake in the preheated oven for 20-25 minutes, or until a toothpick inserted into the center comes out clean.

Cool: Let the cakes cool in the pans for 10 minutes before transferring them to a wire rack to cool completely.

Frost the cake: Once the cakes are completely cooled, spread an even layer of buttercream frosting on top of the first layer. Add any food coloring to the frosting if desired to match the graduation theme. Place the second cake layer on top and frost the entire cake.

Decorate: Add any final decorations such as graduation caps, fondant accents, or themed toppers.

Serve and enjoy: Slice and serve the cake at your graduation celebration!