Preheat oven to 170 °Celsius.

Beat butter and sugar till soft and creamy for about 2 minutes. Add eggs, one at a time, beating well after each addition.

In a separate bowl, sift flour, baking powder, and salt. Fold in the sifted ingredients into the creamed mixture alternately with milk, starting and ending with flour.

Remove cakes from oven and let them cool completely before icing and decorating.

Once the cakes have cooled down, level and fill them with buttercream. And then crumb coat them with buttercream before covering each tier with white fondant.

To make the Hello Kitty cake topper, add some CMC to white fondant, kneaded it well and then roll it to about 1cm thickness. Use the larger Hello Kitty cutter to cut out the Kitty.

And then, while the fondant is still inside the cutter, use the embossing part of the cutter to imprint Kitty’s facial features and bow on the fondant. And then remove both the cutter and embossing tool.

For the bow, use the teardrop and round plunger cutters to make 2 teardrops and one small circle of fondant in pink and attach them onto Kitty's face as its bow.

Next, add all the facial features. To do this, use black fondant. Pinch tiny pieces and roll them into tiny black oval balls and attach them to the face. For the whiskers, roll some black fondant into really thin ropes and attach them to the sides for whiskers. Once that was done, leave the Hello Kitty cake topper aside to firm up.

As for the number topper, again, add a little CMC to pink fondant and cut the number out with a number ‘2’ cutter. Similar to the Hello Kitty cake topper, leave this number 2 topper aside to firm up while you work on the rest of the cake decoration.

To ensure the stripes and scallops consistently spaced out all around the cake, measure the diameter of the cake. Divide the diameter into equal sections. The width of each section will determine the intervals of your pink stripes. Measure the width of each section and draw a circle (with a round cutter as a guide) with a diameter that matches the width of the sections. And then cut the circle into half to make the semi circle template for the cake. Make a few copies of the semi circle templates.

Next, attach the paper templates all around the cake with shortening. Roll pink fondant thin and cut it into strips. Attach the pink stripes to the cake (also with shortening), right at the intersections of each of the semi circle templates. To make sure the stripes are perfectly straight, you can use a rule to adjust them, by pushing them gently into straight lines.

And then, using the round cutter that you used to draw the paper templates earlier, cut the top of each pink stripe to a pointed end. When cutting, apply light pressure and try to leave the semi circle marking on the white fondant to help with the white fondant scallops in the next step.

Remove all the paper templates.

Use the extruder tool to pipe out long strip of white fondant. Attach it to the cake as the scallops. Use the marking on the white fondant (made with the cutter when cutting out the pink strips in the step above) as a guide to attach the scallops. That way you will be able to get perfectly consistent scallops all around the cake.

Next, add the Hello Kitty bows. Make them in the same way as was done for the 3D Kitty topper above and attach them all around the cake.

Roll some pink fondant thin. Cut it out with the plaque cutter.

Roll some white fondant and cut out the letters for the name. Attach them to a pink fondant plaque with shortening.

Carefully lift the plaque and attach it to the front side of the cake and then add a border to it in the same pink fondant. To make the border, use the extruder tool to pipe out a long strip of thin, pink fondant. Attach it all around the plaque with shortening.

To make the 2D kitty faces, roll some white fondant thin. Cut the faces using the smaller Hello Kitty face cutter and attach them to the cake with shortening.

Make the eyes, nose, whiskers and bow in the same way as was done for the 3d Hello Kitty cake topper.

Next, pipe out long strips of pink fondant ropes using the extruder tool. Twist it to make it look like a rope and attach it around the base of both tiers as the cake border.

And finally, add both the Hello Kitty cake topper and the number 2 topper on the Hello Kitty birthday cake with the help of some fondant glue.