Preheat oven to 350 F. Prepare baking pan with parchment paper.
In a medium bowl combine flour and baking powder. Set aside.
In a separate bowl mix butter and sugar with electric mixer until all will become smooth.
Add egg and vanilla extract. Beat until all ingredients will combine.
Combine dry ingredients with wet ingredients.
Mix with mixer, then knead the dough by hand.
Divide the dough into 2 sections. Flour the surface and roll one dough until about 1/4 thick. It depends also how thick you prefer your cookies. Cut the cookies with cookie cutter. Make the same with section 2. Work on the dough until you cutout all cookies.
Lay nicely on parchment paper. Bake for 6 - 10 minutes. Start checking after 6 minutes so they will not burn out.
Cool off cookies completely before decorating.
Melt white and dark chocolate separately using the double boiler method (fill lower pan with water, bring water to simmer, take off from heat, put chocolate chips in top pan and stir).
Decorate your cookies with chocolate and sprinkles.