In stand mixer bowl, add 2 1/2 cups flour, yeast, sugar and salt; mix well. In saucepan or microwave-safe dish, heat buttermilk, water and shortening to 120-130°F (shortening does not need to melt). Add to flour mixture. Add eggs. Using a paddle attachment, blend on low speed for 30 seconds; beat on medium speed for 3 minutes.
Switch to dough hook attachment. Gradually stir in enough remaining flour to make a soft dough. Knead until smooth and elastic, about 5 to 8 minutes.(NOTE: For hand mixing: following above steps, mix ingredients in large mixing bowl using a wooden spoon or dough whisk. Knead on floured surface until smooth and elastic.) Place dough in lightly oiled bowl and turn to grease top. Cover; let rise until indentation remains after poking dough with finger down to second knuckle.
Prepare filling: Combine honey, nuts, raisins, juice concentrate and cinnamon; mix well. Set aside.
Punch down dough. Divide into 2 parts. On lightly floured surface, roll each half to a 12-inch square; spread with half the softened butter from the filling, then half the filling mixture. Roll up tightly, starting with the side nearest you; pinch edges to seal. Cut into 1-inch slices. Place slices horizontally in 4 layers in generously greased Bundt or tubed cake pan, allowing 6 slices per layer. Alternate position of slices in each layer. Cover; let rise in warm place until indentation remains after lightly touching, about 45-60 minutes.
Preheat oven to 350°F.
Bake for 35 to 40 minutes until golden brown. Tent with foil after 20 minutes of baking to prevent over-browning. Invert immediately onto cooling rack.
Prepare glaze: In a small bowl, combine powdered sugar, butter, and 1 tablespoon milk. Blend until smooth, adding additional milk as needed until your desired consistency is reached. Drizzle over cake and serve warm.