In the bowl of a electric stand mixer (see note below) fitted with the paddle attachment, cream the sugar, butter, brown sugar and vanilla on medium speed until light and fluffy, about 4 to 5 minutes. With the mixer on low, add in the eggs one at a time, taking care to fully blend the first before adding the second. Scrape the sides and bottom of the bowl to make sure everything is incorporated. Add in the cream of tartar, baking soda and salt and mix 1 minute more. Add the flour and mix until until just barely combined.