Preheat oven to 350°F. In a medium bowl, whisk together flour, cocoa powder and salt. Using an electric mixer and a large bowl (or a stand mixer), beat butter and 1 cup of sugar on medium-high until light and fluffy (about 3 minutes). Add egg and vanilla and beat until combined. Turn mixer to low and gradually add flour mixture until combined.
Put the remaining 1/2 cup of sugar in a small bowl. Roll dough into approximately 1-inch balls and then toss in sugar to coat. Place one inch apart on parchment-paper or silicone baking sheet lined baking sheets. Bake for 8 minutes or until cookies are set but still look moist. Remove from the oven and lightly press in candy cane kisses into the center of each cookie. Cool completely on the cookie sheets on wire racks before removing to an airtight container to store.