Beach plum thumbprint cookies

Cream one cup of softened butter with two-thirds cup sugar until pale. Work in two cups of flour and a pinch of bay flake salt until it just comes together. Roll into walnut-sized balls, press a thumb into each, and spoon in a little beach plum jam. Bake at 350°F for 14 to 16 minutes until the edges barely color. The jam sets glossy as the cookies cool. Dust with sugar and try to leave some for the guests.