In a mixing bowl take the soft butter and sift the icing sugar into it.
Beat them properly till we get a smooth lump free texture. Now add baking powder and vanilla essence to the bowl. Mix it properly.
Now add the sift flour to the bowl in parts and mix it well till the dough comes together yet would be crumbly.
Now add little by little milk to the dough so it binds well.
Now divide the dough into two parts in the ratio of 1:2. Now divide the larger part into 6 equal portions. Have used weighing scale to divide all the parts equally.
Now to the six smaller parts add red to one of the parts and mix it well. Similarly add orange, yellow, green, blue and violet to each different parts and mix well, as shown in the picture.
Cling wrap all the seven parts and keep it in the refrigerator to set for an hour. Remove the six coloured pieces from the fridge and flatten them in to rectangular shape. Place each piece one above the other carefully by applying water between each layer. Stack them one above the other as shown in the picture.
Gently press from above so all the layers stick with each other properly. Now cling wrap these rectangular pieces and keep it for about an hour in the refrigerator to set properly. The rainbow sheet is ready.
Slice the rainbow sheet. The width should be smaller than the height of your cookie cutter.
Turn each rainbow cookie dough brick, so that you can see the rainbow layers. And make rainbow hearts with a heart cookie cutter. And let set in the refrigerator for 1 hour.
Pile up the rainbow hearts applying water as a glue between the hearts. Cling wrap the heart tower and freeze for 1 hour. Also add ruby and white gel colours to the outer covering layer to get baby pink colour. Mix the dough well and cling wrap it and keep it in the refrigerator.
Now carefully remove them cling wrap and cover the rainbow heart cookie roll with and cover it with cocoa powder. Carefully wet the cocoa powder and then cover the heart roll with small pieces of pink dough and make a cylinder. And let set in the refrigerator for 1 hour.
Brush the dough with water and roll in the colourful sugar balls.
Slice the dough and store in the refrigerator for 30 minutes. Then bake for the cookies in a preheated, 8-10 minutes, kadhai for 20 minutes. Similarly bake all the other cookies.
From the left over cookie dough make round shape and similarly bake them too.
Let them cool on the wire rack. And serve them. You can store them in an air tight container for 2-3 weeks!
