Open a new image size 50 x 50 with a transparent background and 24 bit color. Magnify the image to 500%. Using my guide below, draw the outline with your paint brush settings at: Shape - Round,
Opacity, Thickness and Hardness at 100, Size 1, Blend Mode at Normal. Use the provided color guide to set your foreground color to accordingly, Color #1 for the Icing Outline, Color #3 for the Cake Outline.
I have provided a number representing the length of lines which are
greater than 1 or 2 pixels in length accordingly next to that line.
Use the Magic Wand to select the inside area of the icing and flood fill with color #2 from the color guide and leave selected. Selections float, Effects 3D - Cutout: Vertical & Horizontal both at 0, Opacity at 100%, Blur 15, Color #1 from
the color guide. Leave Selected, Add Noise: Uniform 10% - Monochrome Checked. Deselect.
Use the Magic Wand to select the inside area of the cake and flood fill with color #4 from the color guide and leave selected. Selections float, Effects 3D - Cutout: Vertical & Horizontal both at 0, Opacity at 100%, Blur 15, Color #3 from
the color guide. Leave Selected, Add Noise: Uniform 10% - Monochrome Checked. Deselect. This is what you should have so far:
Next add some shading to the cake by adding lines as shown in the image below using colors #3 and #4 from the color guide. Also add some
texture to the icing by drawing the lines as shown below using color #1 from the color guide.
This is what you should have so far:
Reduce magnification to 100%. That's it, you're done. Enjoy your cupcake!