In a medium mixing bowl, combine flour, baking soda, cornstarch, cream of tartar, and 1 teaspoon of ground cinnamon. Mix using a whisk.
In a large mixing bowl, beat the softened butter and 1 cup of granulated sugar with an electric mixer. Cream for 60-90 seconds on high until well combined and the mixture is fluffy.
Add eggs and vanilla and continue to beat with a mixer for about 30-60 seconds on medium. It will look moist but be consistent in texture throughout.
Gradually add the dry ingredients, one-third at a time on low speed. Beat well between each addition.
Add the toffee bits and mix on low until they are evenly dispersed throughout the cookie dough.
In a small bowl combine the remaining sugar (¼ cup) and ground cinnamon (½ tsp) to create cinnamon sugar.
With a medium cookie scoop, roll cookie dough balls (about 2 tablespoon or 30g). Coat the balls in cinnamon sugar and add to the cookie sheet.
Bake for 10-12 minutes. The edges should be barely golden brown.
Allow the cookies to cool on the tray for 10 minutes before transferring to a wire cooling rack.