• Preheat oven to 350°F; prepare baking sheet with parchment paper
• Sift together flour and baking powder; set aside
• Cream butter and sugars on medium-high until light and fluffy; scrape down sides of bowl
• Add vanilla and mix to combine; scrape down sides of bowl
• On slow speed, add dry ingredients until fully incorporated; shape dough into large disc
• Wrap in plastic; chill in fridge for one hour or overnight
• Divide disc in two; place on lightly floured surface between parchment paper papers
• Roll to ¼ inch thick; cut with cookie cutter and place on prepared baking sheet about ½ inch from one another
• Combine dough a couple of times and continue to roll out and cut into shapes; avoid combining dough more than two times, or it will be tough
• Continue with second disc, repeating the process; bake for 15 minutes, or until lightly browned only around the edges
• Cool on baking sheet for 10 minutes; remove cookies to cool completely on baking rack

Instructions for Icing

• Combine ingredients, and knead (icing "dough" will be the consistency of play dough); divide into two equal portions
• If making sandwich cookies, use one portion to sandwich cookies together, both insides facing toward one another
• Store in air tight container until ready to decorate the top; wrap second portion of icing “dough” in plastic wrap and refrigerate until ready to decorate cookies

Instructions for Making Cookie Dough in Thermomix

• Preheat oven to 350°F; prepare baking sheet with parchment paper
• Place a medium bowl on Thermomix lid; weigh flour and baking powder
• Sift flour and baking powder together; set aside
• Weigh butter and sugar into TM bowl; whisk at 3.5 for 2 minutes until until light and fluffy; scrape down sides of bowl
• Add vanilla and whisk at 3.5 for 15 seconds to combine; scrape down sides of bowl
• Place pre-weighed and sifted dry ingredients into TM bowl; fold dry ingredients into wet for 30 seconds at speed 3
• Scrape down sides of bowl; repeat for 30 seconds at speed 3 until fully incorporated, but do not over mix
• Dough will be very moist; plop onto plastic wrap, shape into large disc, wrap well, and refrigerate for one hour or overnight
• Divide disc in two; place on lightly floured surface between parchment paper papers
• Roll to ¼ inch thick; cut with cookie cutter and place on prepared baking sheet about ½ inch from one another
• Combine dough a couple of times and continue to roll out and cut into shapes; avoid combining dough more than two times, or it will be tough
• Continue with second disc, repeating the process; bake for 15 minutes, or until lightly browned only around the edges
• Cool on baking sheet for 10 minutes; remove cookies to cool completely on baking rack

Instructions for Making Icing in Thermomix

• Weigh ingredients into TM bowl; combine for 15 second at speed 3.5
• Knead for 30 seconds; remove from bowl; divide into two equal portions
• If making sandwich cookies, use one portion to sandwich cookies together, both insides facing toward one another
• Store in air tight container until ready to decorate the top; wrap second portion of icing “dough” in plastic wrap and refrigerate until ready to decorate cookies

Decorating the Onsie Butter Cookies (Give your self lots of time for this)

• Remove cold icing disc from refrigerator and place cookies nearby
• Divide disc of icing into two; roll ½ onto parchment paper a good 1/8 inch thick (thin, but not too thin)
• Refrigerate rolled icing on baking sheet at least 30 minutes
• Repeat with the other ½ of the disc of icing
• Press cookie cutter firmly into icing; use an offset spatula to carefully move the chilled firm cut out icing shape off of the cutting board
• Brush cookie lightly with water; gently slide cut out icing shape onto lightly damped cookie top with spatula
• Repeat until all cookies are topped with an exact cut out of icing: this will mean combining and recombining leftover portions of icing “dough”, rolling, chilling, cutting out and repeating the process until all cookies are topped with icing
• Decorate with gel colours, pearls, dragees, sprinkles, sparkling sugar or a combination; freeze or refrigerate in tightly sealed container until ready to serve