Preheat Oven: Preheat your oven to 350°F (175°C). Prepare two 8-inch round cake pans by greasing and flouring them, or by lining them with parchment paper.

Mix Dry Ingredients: In a medium bowl, whisk together 2 ½ cups all-purpose flour, 2 ½ tsp baking powder, and ½ tsp salt. Set aside.

Cream Butter and Sugar: In a large bowl, beat 1 cup unsalted butter and 1 ½ cups granulated sugar together until light and fluffy.

Add Eggs: Add 4 large eggs one by one, mixing thoroughly after each addition.

Combine Wet Ingredients: Mix in 1 cup milk and 1 tsp vanilla extract.

Combine Dry and Wet Ingredients: Gradually add the dry ingredients to the wet mixture, mixing until just combined. If using, fold in ½ cup strawberry bits.

Pour and Bake: Divide the batter evenly between the prepared cake pans. Bake in the preheated oven for 25-30 minutes, or until a toothpick inserted into the center comes out clean.

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

Cream Butter: In a large bowl, beat 1 cup unsalted butter until creamy.

Add Powdered Sugar: Gradually add 4 cups powdered sugar, beating on low speed until combined.

Adjust Consistency: Add 2-4 tbsp milk or heavy cream, one tablespoon at a time, until the frosting reaches your desired consistency.

Flavor and Color: Mix in 1 tsp vanilla extract and, if desired, a few drops of pink food coloring until the color is evenly distributed.

Level the Cakes: Once completely cooled, level the tops of the cakes using a cake leveler or knife to ensure even layers.

Stack the Layers: Place one cake layer on the cake board or serving plate. Spread a layer of buttercream on top. Place the second layer on top and press down gently to secure.

Crumb Coat: Spread a thin layer of buttercream all over the cake to trap any crumbs. Chill the cake for about 30 minutes to let the crumb coat set.

Apply Final Coat: After the crumb coat has set, apply a smooth, even layer of buttercream over the entire cake.

Use a Template: If using a Hello Kitty cake pan or stencil, follow the instructions for creating the Hello Kitty design.

Pipe Decorations: Use a star-shaped piping tip to create decorative borders or patterns. Add any additional decorations like edible bows or flowers if desired.

Detailing: For extra detail, use different colors of buttercream or fondant to add facial features like Hello Kitty’s eyes, whiskers, and bow.