Preheat oven to 375. Combine filling ingredients, minus the peanut butter, in a small bowl, then mix with a fork until well blended.
In a another, larger bowl, combine flour, sugar, baking powder, baking soda and salt. Mix together buttermilk and melted butter in a separate bowl, then pour into the middle of the dry ingredients. Stir together until dough just comes together, being mindful not to over-mix. Knead slightly by hand until the dough forms into a ball.
On a lightly floured surface roll out dough into a long rectangle, about ¼ inch thick. Spread the peanut butter over the entire surface of the dough, then press the sugar filling onto the peanut butter.
Using a pizza cutter or knife, cut the dough length-wise, into 2-inch-wide strips. Roll the first strip from end to end and place in the center of a greased pie plate. Take the next strip and wrap it around the first piece, in a spiral. Repeat with each strip until the pie plate is full.
Back for 20 minutes, or until the top is golden brown.
While the cake is baking, combine the cream cheese, powdered sugar, and milk in a small blender and blend until smooth. Melt the chocolate and peanut butter in the microwave for 15 second intervals, stirring in between, until melted. Drizzle both icings onto the hot peanut butter cinnamon roll cake and spread evenly.