Preheat oven to 350 F degrees. Unwrap 36 Hershey's Kisses and set aside.
In a large bowl, beat ⅓ cup butter, ¾ cup white sugar, and ½ cup brown sugar until fluffy.
Add ⅓ cup Greek yogurt and 1 egg and beat until smooth.
In a medium bowl, whisk 1 ½ cups flour, ⅔ cup cocoa powder and 1 teaspoon baking soda. Stir flour mixture into butter mixture until just incorporated.
Using Tablespoonfuls of dough, gently roll cookies into balls and roll in sugar. Place 2 inches apart onto parchment lined baking sheet.
Bake for 8 minutes. Remove from oven and let cool for 1-2 minutes, then place Hershey's Kiss on top, pressing down gently. Do not move the cookies until they are completely cool and the kiss has a chance to set back up (or your little kiss top might flop).
Store cooled cookies in airtight container.
Makes about 3 dozen cookies.