Use an electric mixer to beat the powdered sugar with the butter, heavy cream and vanilla extract until thick and smooth. Spread the glaze over the warm cinnamon rolls.
Prepare Dough: In large mixer bowl, combine 1+1/2 cups flour, yeast, sugar and salt; mix well. In saucepan, heat milk, water and butter (or shortening) until warm (120-130°F; butter does not need to melt). Add to flour mixture. Add egg. Blend at low speed until moistened; beat 3 minutes at medium speed. By hand, gradually stir in enough remaining flour to make a soft dough. Knead on floured surface until smooth and elastic, 5 to 8 minutes. Place dough in lightly oiled bowl and turn to grease top. Cover; let rise until dough tests ripe.
Prepare Filling: Combine brown sugar, granulated sugar, and cinnamon; set aside.
Punch down dough. On lightly floured surface, roll to a 15 x 12-inch rectangle. Spread with softened butter. Sprinkle Filling over dough. Starting with shorter side, roll up tightly. Pinch edge to seal. Cut into 12 slices. Place in greased 13 x 9-inch cake pan. Cover; let rise in warm place until indentation remains after touching. Bake at 375°F for 20 to 25 minutes until golden brown. Remove from pan;
*You can substitute Instant (fast-rising) yeast in place of Active Dry Yeast. When using Instant Yeast, expect your dough to rise faster. Always let your dough rise until ripe. Traditional methods: use equal amounts; Bread Machine: use ½ tsp Instant Yeast OR ¾ tsp Active Dry Yeast per cup of flour in your recipe.