Take butter and sugar in a bowl.
Beat them with electric beater until they turns soft and fluffy. You can use hand whisk too to beat the mixture.
Add flour, corn starch, baking powder, baking soda, salt and vanilla essence.
Give them a good mix.
Add 1 tbsp of sprinkles.
Mix well forming a soft dough.
Scoop out a tsp of dough using a scooper or spoon.
Roll the dough into a ball inside your palm.
Gently press the ball very lightly giving it a flat cookie shape.
Coat one side of the cookie with Sprinkles.
Likewise make more cookies and arrange them on a baking tray lined with greased butter paper or parchment paper. Do keep some distance between all the cookies because they are going to expand while baking.
Put the tray in refrigerator for 1 hour.
Bake them in a preheated oven @180°C for 12 to 15 minutes or until their corners begin to turn slightly brown.
Once done, take them out and let turn cool completely.
Funfetti cookies are ready.
Enjoy.