In a food processor** cream together butter and sugar until just mixed add egg, pulse a few times, add vanilla and again pulse a few times. Add dry ingredients and mix just until dough starts to come together. Remove from bowl to a lightly floured flat surface and gently knead until combined (do not over knead). Wrap in plastic and refrigerate one hour.
Pre-heat oven to 350° (180° celsius), line cookie sheets with parchment paper.
Remove dough from fridge, roll on a lightly floured flat surface to desired thickness, cut out cookies, place on prepared cookie sheets, and refrigerate again for 10 minutes.
Bake for approximately 10-15 minutes (depends on thickness), cookies should be pale but baked (I baked mine for 11 minutes).
In a small bowl over boiling water (make sure water does not touch the bowl). Melt dark or milk chocolate.
Let cookies cool completely before spreading with chocolate, I always find it easier to first drizzle some chocolate on the cookie with a spoon then spread the chocolate to cover with the back of the spoon instead of dipping. Place on rack (as shown in photo) and sprinkle with sprinkles, small hearts etc. Enjoy!
**If you don't have a food processor you could also use a mixer with the paddle attachment but don't over beat and follow the directions for the food processor.