Preheat oven to 350 degrees. Melt butter and mix in cocoa. Allow to cool. Add honey, eggs, sugar, flour, baking powder, and salt. Mix well. Add nuts. Pour batter into a greased or parchment paper lined 9-by-13 baking pan. Bake at 350 degrees for 20-25 minutes. Cool completely.
Prepare frosting: In a medium bowl, beat butter, powdered sugar, corn syrup, milk, and salt on low-speed until combined. Beat until fluffy. Add more milk as needed until frosting is thinner than cake frosting. We will now divide the frosting in half and make one mint and one chocolate. Take half of the frosting out and place in another bowl for the mint frosting. The frosting remaining in the bowl will be the chocolate frosting.Mint frosting: Stir in the peppermint extract and green dye by hand or with a mixture. Spread mint icing over brownies. Place brownies in the freezer for a short time to stiffen the icing (very important step). Remove from the freezer and carefully add a layer of chocolate frosting.
For the Chocolate Frosting: Add cocoa. Mix until smooth. Spread chocolate icing over mint frosting. Refrigerate until firm. Cut into squares and serve.