1. Prepare the cake. Preheat oven to 350 degrees F. Spray an 8- or 9-inch square pan with vegetable cooking spray. Use a paper towel to make sure pan is evenly greased.
2. In a medium bowl, stir together cocoa, flour, baking soda, and salt. Set aside.
3. In a large mixing bowl, combine butter and sugar. Using an electric mixer on medium speed, mix until light and fluffy, about 2 minutes. Add the egg and mix on medium speed until combined. Add vanilla and mix until combined. Add half the dry mixture and mix until just combined. Add the buttermilk and mix until just combined. Add remaining dry mixture and mix until smooth and fluffy.
4. Pour batter into prepared pan. Bake at 350 degrees F until a toothpick inserted in the center of the cake comes out with a few moist crumbs, 20 to 25 minutes. Cool in the pan about 5 minutes, then run a knife around the edge to loosen the cake before transferring it to a wire rack to cool completely, about 20 minutes. (Cake may be made a day in advance. Cover and store at room temperature.)
5. Once the cake is cool, prepare the frosting. In a large mixing bowl, beat butter using an electric mixer on high speed until light and fluffy, about 1 minute. Add melted chocolate and beat until smooth. Add confectionersf sugar and mix until combined. Add buttermilk and mix on high speed 30 to 60 seconds, or until frosting is smooth and fluffy. If mixture is dry, add additional buttermilk, 1/2 tsp. at a time.
6. Crumble the cake into the frosting bowl. Mix on low speed about 10 to 20 seconds, or until mixture comes together like dough.
7. Prepare the cake pops for decorating. Line a baking sheet with parchment or wax paper. Divide the dough into 24 pieces, about a heaping tablespoon for each portion. Roll each portion into a smooth ball and arrange on the baking sheet. Push a pretzel stick into the center of each ball, pushing down and molding the dough around the stick. Refrigerate 1 hour.
8. Prepare the decorating chocolate. Melt chocolate with butter in a double boiler over low heat or in a microwave. Stir until smooth, then turn off heat. Chocolate should be just slightly warm to the touch. Holding the pretzel, dip the top 2/3 of each cake pop into the chocolate, twirling the pop to remove excess chocolate. Use a knife to spread the chocolate down so that it coats all the cake and a little bit of the pretzel. If desired, roll coated pop in sprinkles or chopped nuts, or decorate with small candies, then place coated pops back on the lined baking sheet with pretzel sticking straight up. (The top of the pops will flattenslightly, similar to candy apples.) Let set in the refrigerator until firm, about 30 minutes. Store in an airtight container in the refrigerator or freezer. Serve slightly chilled.
Source: Hannaford fresh Magazine, September - October 2009