Combine 1-1/2 cups flour, undissolved yeast, sugar and salt in a large mixer bowl. Heat water and butter until very warm (120 to 130°F). Note: butter may not melt completely. Add to flour mixture with egg. Beat for 2 minutes until well mixed. Gradually add enough remaining flour until soft dough forms.
Knead on a lightly floured surface until smooth and elastic about 4 to 6 minutes. Cover and let dough rest 10 minutes.
Roll dough on a lightly floured surface to a 12 x 15-inch rectangle. Spread with softened butter. Combine sugar and cinnamon; sprinkle over surface. Roll up tightly, lengthwise. Slice into 12 equal rolls. Grease two 9-inch round pans.
To form hearts, take one roll and gently unroll about half. Reroll this portion towards the center, forming 2 round rolled portions (like a scroll - which makes the rounded part of the heart). Pinch the end of each roll to form a point. Repeat with remaining rolls. Place 6 rolls in each pan with points toward the center. Cover. Let rise 30 to 45 minutes until nearly doubled.
Bake in preheated 350°F oven for 18 to 23 minutes. Cool for 15 minutes; remove from pan.