In the stand mixer, briefly mix the butter and sugar. Just as the butter and sugar come together, stop mixing. (The more the sugar and butter is creamed the fluffier the cookie will be.) Scrape down the sides.
Add the egg and vanilla. Turn the mixer on medium and mix until the egg is completely incorporated.
Lastly, add all the flour. You can either put a towel over your mixer until everything is incorporated or start out on the stirring setting of the mixer until the flour started to incorporated. Once the flour is mixed in some, go ahead and turn the mixer on medium and let it mix until the flour is combined with the creamed mixture.
Cut the dough in half and roll one half between two pieces of parchment paper. Take the top piece of parchment paper off and cut the cookies with preferred cutters.
Place on cookie tray with either a silicon mat or parchment paper. (I cut all my cookies out and stacked them on the cookie sheet. I used parchment paper to separate the cookies)
Place in the freezer for at least an hour.
Preheat your oven 350 and bake 10-12 minutes or until it's done. The bottoms of the cookie and sides will start to brown. That's a sure sign they're done.
Let the cookies cool and frost.
Notes
Since my shamrock cutter is humongous and I like my cookies pretty thick I baked my cookies at 325 for 18-20 minutes.