Melissa Clark's Cultured Butter Cookies

A homely little cookie that I would want to hoard for myself at home.
I rolled 1/2 in demarara sugar-- kind of disappeared, lookswise and texturewise, since the cookie is already crumbly and crisp. I rolled the other half in red and green sugar, also a looks mistake. I should have gone with a single color, red OR green. Or fine toasted coconut! Or very finely chopped nuts! NOW I'm talking!

150 g AP flour (2 cups)
3 g baking powder (1/2 t)
1/4 t salt
2 sticks salted, cultured butter, at room temperature (1 c)
130 g granulated sugar (2/3 c)
1 large egg yolk
55 g demarara sugar, for rolling, or something else

Sift together flour, baking powder, salt.

Cream butter and sugar until lightened and fluffy; beat in yolk until combined. On low or by hand, add dries until incorporated.

Divide dough into two balls. Roll each ball into a 1 1/2 inch log. Sprinkle whatever coating you're using over a sheet of parchment, and roll each log in it until the outside of the dough is thoroughly covered. Cover logs tightly with plastic wrap and refrigerate at least one hour, or overnight.

Heat oven to 325 F. Parchment your sheets. Use a shrap knife to cut logs into 1/4 inch thick rounds. Bake until cookie edges and bottoms are dark golden brown, about 18 minutes. Cool 5 minutes on baking sheets, then transfer to wire rack to cool completely.