Preheat oven to 350°F. Fill muffin tins with cupcake liners.
In a mixer blend cake mix, water, oil and eggs for a few minutes.
Fill cupcake liners 2/3 full of cake batter.
Bake 19-23 minutes. When a toothpick inserted in the center comes out clean, your cake is done. Cool 10-15 minutes.
Make frosting by whipping butter, cream cheese and powdered sugar until fluffy.
Add one drop of black food coloring and 1-2 drops of pink food coloring. Keep adding drops until you get a yucky grayish pink color of brains.
Assemble your brains in a jar cake by placing a cupcake inside of a half pint mason jar.
A a large spoonful of raspberry jam over the cake, covering the surface and making sure it reaches the edges of the jar.
Put some frosting in a piping bag with a #5 round tip Hold the bag at a 90 degree angle and squiggle the frosting along the edges of the jar. It doesn't have to be perfect, just squeeze and make a zig zag motion along the inside of the glass.
Cut small pieces of another cupcake and place in the center of the "brain frosting".
Holding the piping bag at a 90 degree angle again, loosely squeeze frosting all over the top of the cake.
Place lid on the jar and add the Brains in a Jar Printable Tags and serve.