Preheat oven to 375°F. Line a large baking sheet with parchment; set aside.
In a large bowl, combine hotroll mix with yeast (included in box), sugar, 2 Tbsp. butter and 1 cup hot water. Mix until a ragged dough forms. On a floured surface, knead dough for 5 minutes place it in a lightly oiled bowl and turn to coat. Cover; let rise in a warm place for 35 minutes.
Pour 2 cups boiling water over cherries. Soak for 15 minutes; drain.
In a bowl, mix cherries, chocolate, cocoa, flour, brown sugar, almond extract and remaining 4 Tbsp. butter.
Roll out dough into a 12- by-18-inch rectangle (long side closest to you). Spread with cherry filling, leaving a 3-inch border along longer sides and a 1-inch border along shorter sides.
Gently roll dough away from you, creating a long cylinder; pinch seam to seal. Position cylinder so seam faces down. Curve cylinder ends together to form a ring and pinch ends together to seal. Place ring on prepared baking sheet. Cut 16 evenly spaced slices, but cut only two-thirds into ring, keeping inner edge of ring intact. Give each slice a 1/4 twist so filling is exposed. Beat egg and 1 Tbsp. water; brush over ring.
Bake until golden brown, 30 to 35 minutes. Cool on baking sheet for 5 minutes. Using two spatulas, transfer ring to a wire rack; cool. Whisk together confectioners' sugar and milk to form a glaze, and then drizzle over cooled coffee cake.