To prepare roll, dissolve yeast and 1 teaspoon granulated sugar in 1/4 cup warm water in a small bowl; let yeast mixture stand 5 minutes.
Spoon cake flour into dry measuring cups; level with a knife. Combine 2 cups cake flour, 1/2 cup granulated sugar, and salt in a large bowl. Add warm buttermilk and egg; beat with a mixer at medium-low speed for 30 seconds. Add yeast mixture, and beat 1 minute. Add remaining 1 cup cake flour, and beat for 1 minute. Lightly spoon all-purpose flour into dry measuring cups; level with a knife. Stir in 1 cup all-purpose flour to form a soft dough. Turn dough out onto a floured surface. Sprinkle surface of dough with raisins. Knead until smooth and elastic (about 8 minutes); add enough of remaining all-purpose flour, 1 tablespoon at a time, to prevent dough from sticking to hands.
Place dough in a large bowl coated with cooking spray, turning to coat top. Cover and let rise in a warm place (85°), free from drafts, 1 1/2 hours or until doubled in size. (Gently press two fingers into dough. If indentation remains, dough has risen enough.) Punch the dough down. Divide into 3 pieces. Cover and let stand for 5 minutes (dough will feel sticky).
Combine brown sugar, cinnamon, and cocoa in a small bowl. Working with one portion of dough at a time (cover remaining dough to prevent drying), roll dough into a 16 x 6-inch rectangle on a lightly floured surface. Brush surface of dough with 1 tablespoon butter, and sprinkle with one-third of brown sugar mixture. Roll up tightly, starting with a long edge, pressing firmly to eliminate air pockets; pinch seam and ends to seal. Repeat procedure with the remaining dough, butter, and brown sugar mixture. Braid the 3 rolls, pinching ends to seal. Place braid in a 9-inch springform pan coated with cooking spray, forming a ring. Cover and let rise 1 hour or until doubled in size.
Preheat oven to 350°.
Uncover dough, and bake at 350° for 25 minutes. Lightly cover with foil; bake 20 minutes or until golden brown and loaf sounds hollow when tapped. Cool 10 minutes in pan on a wire rack. Remove from pan; cool on wire rack.
To prepare glaze, place powdered sugar, cream cheese, and vanilla in a medium bowl; beat with a mixer at low speed just until blended. Stir in fat-free milk. Drizzle over bread. Cool to room temperature before serving. Cut into wedges.