Preheat oven to 350 degrees.
Measure out the dry ingredients together in a small bowl, set aside.
Using a mixer, cream together the butter and sugar.
Add the egg and vanilla, mix again until creamy.
Add the dry ingredients and mix to combine, If using the nuts, stir them in at the end by hand.
Drop by teaspoons onto a cookie sheet lined with parchment paper, bake for about 10 minutes. Remove from pan and allow them to cool on a baking rack.
For the frosting - When the cookies are done baking, make the brown butter. Brown slightly.
Using a stand mixer, beat the vanilla and powdered sugar. Slowly add the brown butter. Beat until light and fluffy.
Frost the cookies and dust with sprinkles if desired