Combine cinnamon and 3 tablespoons sugar; set aside.
Combine 5 cups flour and yeast in a mixing bowl. Combine water and milk; gradually add to flour mixture, beating at medium speed of a heavy-duty stand mixer until well blended.
Combine squash, molasses, oil, and salt; add to flour mixture, beating well. Add enough of remaining flour, 1 tablespoon at a time, to form a soft dough.
Turn dough out onto a lightly floured surface. Knead until smooth and elastic (about 10 minutes), adding enough of remaining 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, 25 minutes or until doubled in bulk. Punch dough down; turn dough out onto a lightly floured surface, and knead 5 times. Divide dough in half. Working with 1 portion at a time, (cover remaining dough to keep it from drying out), roll each portion into a 16- x 7-inch rectangle. Brush each with 1 tablespoon melted butter; sprinkle with half of reserved cinnamon-sugar mixture and half of raisins. Roll up each rectangle tightly, starting with short side. Press firmly to eliminate air pockets; pinch seam and ends to seal. Place each roll of dough, seam side down, in a 9- x 5-inch loaf pan coated with cooking spray. Cover and let rise 20 minutes or until doubled in bulk.
Preheat oven to 350°.
Bake at 350° for 30 minutes or until loaves sound hollow when tapped. Remove from pans immediately, and let cool on wire racks.
Combine powdered sugar, milk, and vanilla, stirring well. Drizzle over loaves.