4-in-1 Shortbread Cookies

1.	TO MAKE THE SHORTBREAD COOKIE DOUGH:
2.	Beat butter until smooth and creamy, 2-3 minutes. Add sugar and vanilla, and beat for an additional 2-3 minutes until light and fluffy. Stop and scrape down the bowl a few times as needed.
3.	Add flour and salt and mix until dough comes together. It will be dry and shaggy but should hold together when pressed.
4.	TO MAKE FLAVOR VARIATIONS:
5.	Divide shortbread dough into 4 bowls and add mix-ins to the bowls (see Notes).
6.	Use your hands to work the mix-ins into the dough and press it together into a log about 4 inches wide. Wrap each in plastic wrap, using the plastic wrap if needed to encourage the dough together.
7.	Chill in the fridge for 1 at least hour, and up to 1 week.
8.	TO BAKE COOKIES:
9.	When ready to bake, preheat oven to 350°F.
10.	Use a sharp knife to slice cookie dough log into ¼-inch rounds. Place rounds on a sheet pan lined with parchment paper.
11.	Bake cookies until they appear dry and set, about 12-15 minutes. The bottoms should be lightly browned underneath (lift a test cookie with a spatula to check). For crisper cookies, bake until bottom edges appear lightly browned.
12.	If adding coarse sugar or flaky salt, sprinkle over cookies when they are hot from the oven. Let cookies cool on the pan for 5 minutes, then transfer to a wire rack to cool completely.
13.	If adding melted white or dark chocolate, drizzle over the top of cooled cookies, or dip a corner of the cookie. Place on parchment or wax paper to set up.

	1 ½ cup Salted Challenge Butter , at room temperature (3 sticks, 340 grams)
	1 cup granulated sugar (100 grams)
	1 cup granulated sugar (100 grams)
	3 ¼ cup all-purpose flour (390 grams)
	¼ teaspoon salt
	FOR DARK CHOCOLATE ESPRESSO COOKIES:
	¼ cup chopped bittersweet or dark chocolate
	¼ teaspoon instant espresso powder
	FOR NUTTY CINNAMON COOKIES:
	¼ cup chopped nuts , like pecans, walnuts, etc.
	¼ teaspoon ground cinnamon
	FOR WHITE CHOCOLATE AND TOASTED COCONUT COOKIES:
	¼ cup chopped white chocolate
	¼ cup toasted coconut
	FOR CRANBERRY ORANGE COOKIES:
	¼ cup chopped dried cranberries
	2 tablespoons candied orange peel