In a large mixing bowl or stand mixer, beat butter until creamy. Add sugar and beat on medium high until light and fluffy, about 2-3 minutes. Stir in vanilla until combined. Add flour and mix until well combined, but do not over mix.
Remove 2/3 of dough mixture from the bowl (leave 1/3 of dough IN the mixing bowl), and place dough evenly divided into two bowls.
For Chocolate Chip Shortbread, add chocolate chips to one bowl of dough and stir well to combine. Form dough into the shape of a log, approximately 1 and 1/2 inches thick. Wrap tightly with plastic wrap and place in fridge to chill.
For Cranberry Orange White Chocolate Shortbread, add white chocolate chips and chopped dried cranberries to one bowl of dough, and stir well to combine. Form dough into the shape of a log, approximately 1 and 1/2 inches thick. Wrap tightly with plastic wrap and place in fridge to chill.
For Peppermint Shortbread, add 1 teaspoon peppermint extract and 25-50 drops of red food coloring to dough (depending on shade desired) and mix well with mixer. If dough seems sticky, add in 1 to 2 extra tablespoons of flour. Form dough into the shape of a log, approximately 1 and 1/2 inches thick. Wrap tightly with plastic wrap and place in fridge to chill.
Chill all doughs for at least two hours. In a rush? Dough can be placed in freezer for one hour for a quick short cut.
When ready to bake, preheat oven to 350 degrees F.
Remove one log of dough from fridge. Allow to sit at room temperature for approximately five minutes. Using a sharp knife, cut into 12 equal sized pieces. If dough flakes slightly when cutting, use hands to help push dough together, the warmth of your hands will do this easily. Place cookies onto a baking sheet lined with parchment paper or a silicone baking sheet. For Chocolate Chip Shortbread, feel free to sprinkle tops of cookies with coarse sugar. Bake for approximately 12 minutes, or until bottoms are starting to lightly brown. Remove from oven and allow to cool completely. Repeat with remaining two logs of dough.