Preheat oven to 375 degrees F. Line a cookie sheet with parchment paper.
Add the butter and sugar to a large bowl. Using a hand mixer, beat on medium until creamed.
Add in the egg and vanilla. Beat until combined. Set aside.
In a separate bowl, add the flour and salt. Whisk until incorporated.
Add the dry ingredients in with the wet and beat until the flour is just incorporated.
Cover with plastic wrap and refrigerate the dough for 15 minutes.
Using a 1 tablespoon cookie scoop, scoop the dough into your hands, roll into balls, and place on the prepared cookie sheet. I grabbed a potato masher, but a whisk would also make a pretty design, and pressed it into the cookie dough.
Place in the preheated oven and bake for 8-10 minutes, until the edges start to turn a golden brown. Allow the cookies to cool on the cookie sheet for 5 to 10 minutes before transferring to a cooling rack or paper towel to cool completely.
Chocolate
Using a microwave-safe bowl, microwave the chocolate and oil together in the microwave for 15 seconds intervals, stirring between each time.
Once the chocolate is completely melted, dip each cookie into the chocolate, allow the excess drip off, and then place it on a piece of wax paper.
Before the chocolate dries, add some sprinkles to the chocolate.
Store in an airtight container at room temperature for up to 5 days.
Notes
To pipe these butter cookies, add 1 to 2 ½ tablespoons of milk to the recipe after adding the flour and salt. You want the dough to still be thick, but also creamy and pipable. The more milk you add to the recipe, the more the cookies will spread. So add as little as possible. Place the cookie dough in a piping bag with a large star tip and pipe swirls on a parchment lined cookie sheet and refrigerate for 30 minutes or more to help prevent spreading. Bake as directed above.