Preheat your oven to 350°F (175°C).

In a large mixing bowl, cream unsalted butter and granulated sugar together on medium speed for 2–3 minutes until light and fluffy.

Add all-purpose flour, ground cinnamon, and salt into the bowl. Mix on low speed until the dough comes together.

Shape the dough into a flat disk, wrap in plastic wrap, and chill in the refrigerator for at least 1 hour.

On a floured surface, roll out the dough to about 3/8 to 1/2 inch thick.

Cut dough into rectangles measuring 3x1.5 inches, sprinkling turbinado sugar on half of each rectangle.

Transfer cookies to baking sheet and bake for about 12 minutes, until pale and slightly firm. Cool slightly before transferring to a wire rack.

Melt dark or bittersweet chocolate in a microwave-safe bowl or double boiler, stirring until smooth.

Dip the sugar-free half of each cooled cookie into the chocolate and place on parchment paper.

Sprinkle additional turbinado sugar onto the wet chocolate before it sets and allow cookies to cool completely.