DOUGH: In a small saucepan, warm the milk over low heat until it reaches 95-100 degrees. Pour the warm milk into the bowl of a standing electric mixer; stir in the sugar and yeast. Let stand until the yeast is foamy, about 5 minutes.
Whisk in softened butter, eggs, and sea salt, until combined. Attach the dough hook to the mixer. Add flour to the bowl. Mix on low speed until a soft dough forms, about 3 minutes. Increase the speed to medium-high and beat until the dough is smooth, about 5-7 minutes longer. Add ½ cup chopped peppermint bark and mix until evenly distributed in dough.
Form the dough into a ball; transfer the dough ball into a large lightly buttered bowl. Cover with plastic wrap or a tea towel and allow dough rise in a warm place until dough has doubled in volume, about 1-2 hours.
Meanwhile, line the bottom of a 9 x 13-inch baking pan with parchment paper, allowing the paper to extend up two sides. Butter the paper and sides of the pan; set aside.
Punch down raised dough. Turn the dough out onto a lightly floured work surface. Using a rolling pin, roll the dough into a 20 x 14-inch rectangle.
CHOCOLATE FILLING: Spread 1/3 cup softened butter over dough.
In a small bowl, mix together cocoa powder and sugar. Evenly sprinkle the cocoa/sugar mixture over dough. Top with 1 cup chopped peppermint bark on top.
Roll dough into a log, starting at the longer side. Slice the log into 12 equal parts (about 1 3/4- inches each). Place rolls in prepared 9 x 13-inch baking pan. Cover with plastic wrap or a tea towel, allow rolls to rise in a warm place until they are puffy and have filled the pan, about 1 hour.
Preheat oven to 400 degrees. Remove plastic wrap and bake rolls for about 25 minutes until golden brown on top. Loosely cover rolls with foil halfway through baking to prevent them from getting too dark. Transfer the pan to a rack to cool for 30 minutes. Meanwhile, prepare frosting
CREAM CHEESE FROSTING: In a medium bowl, beat together softened cream cheese and butter until smooth. Add confectioners’ sugar, salt, and vanilla; continue to beat until smooth and creamy. Add milk if too stiff. Spread over warm rolls. Top with 1 cup chopped peppermint bark and devour!