Preheat the oven to 350 F. In a medium bowl, whisk together flour, salt, and baking soda. In a large bowl, mix together butter and sugar until fluffy. Add in egg and vanilla extract and mix until smooth.
Add in the flour mixture, and mix until it is fully combined. In a shallow dish, combine granulated sugar and ground cinnamon.Roll the cookie dough into balls and roll in the cinnamon sugar mixture. Place cookies onto a large ungreased baking sheet at least 2-inches apart. Bake for 10-12 minutes.
Place mini peanut butter cups on each cookie and decorate with icing and candy eyes.
