Heat the sour cream in a small saucepan over medium heat to 105 to 115 degrees F. (use a thermometer). Combine warm sour cream, melted butter, sugar, salt and soda in large mixing bowl. Add yeast, then egg; mix well. Add 1 1/2 cups flour and beat until well blended. Gradually stir in enough remaining flour to make a soft dough (you may not need to use it all).
Turn the dough onto a lightly floured surface and knead lightly 5 or 6 times. Cover and let dough rest 10 minutes.
Roll dough into an 18x6 inch rectangle. Spread 3 tablespoons of melted butter over the dough. Sprinkle the brown sugar and cinnamon over the dough (add a few nuts and raisins at this point if you want).
Roll up the dough, starting at long side, pressing firmly to eliminate air pickets and pinching seam to seal. Slice into 1½ inch slices and place cut-side down in greased muffin pans. Cover and let rise in warm place until doubled in size (about an hour).
Bake in preheated 375 degree oven for 12 to 15 minutes, or until golden brown. Set on the counter to cool.
ICING
Combine the cream cheese with the butter, using an electric mixer to beat until smooth. Add powdered sugar and vanilla.