Melt butter over low heat in a heavy-bottomed saucepan.

Once melted, the water in the butter evaporates quickly and bubbles form. Swirl constantly to reduce splatter.

When the butter starts to foam, stir constantly and scrap the bottom so the milk solids don’t stick and burn.

As soon as dark golden specks appear and it smells nutty & toasty, immediately remove from heat and pour into a mixing bowl.

Let cool for several minutes, then beat in water, sugars, espresso, vanilla, cinnamon, and salt.

Slowly add flour and beat just until combined.

Scoop dough onto a large piece of plastic wrap. Roll into a log about 1½" wide and seal tightly. Freeze for at least 30 minutes.

Preheat oven to 325°.

Unwrap the dough and slice log into quarter-inch pieces. Arrange on a baking sheet lined with parchment paper.

Bake at 325° for 8-10 minutes, until edges are set and center is still soft.

Transfer to a wire rack to cool and immediately dust tops with sugar.