How to Make It
To prepare bread, dissolve yeast and 1 tablespoon granulated sugar in warm milk in a large bowl; let stand 5 minutes. Stir in 1/4 cup butter, vanilla, and egg yolks. Lightly spoon flour into dry measuring cups, and level with a knife. Add 4 1/2 cups flour, 3 tablespoons granulated sugar, and salt to yeast mixture; stir to form a soft dough. Turn dough out onto a floured surface. Knead until smooth and elastic (about 10 minutes); add enough of remaining flour, 1 tablespoon at a time, to prevent dough from sticking to hands (dough will feel tacky).
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, 1 hour or until doubled in size. Punch dough down, and let rest 5 minutes. Divide in half. Working with one portion at a time (cover the remaining dough to keep from drying), roll each portion into a 14 x 7-inch rectangle on a floured surface. Combine the brown sugar and cinnamon. Sprinkle each dough portion with half of brown sugar mixture, leaving a 1/2-inch border. Roll up each dough rectangle tightly, starting with a short edge, pressing firmly to eliminate air pockets, and pinch seams and ends to seal. Cut each dough roll crosswise into 3 pieces. Place 3 pieces, cut sides up, into each of 2 (8 x 4-inch) loaf pans coated with cooking spray. Cover and let rise 30 minutes or until doubled in size.
Preheat oven to 350°.
Uncover dough, and bake at 350° for 35 minutes or until loaves are browned on bottoms and sound hollow when tapped. Cool in pans 10 minutes on a wire rack, and remove from pans. Brush tops of loaves with melted preserves. Cool loaves on rack.
To prepare the glaze, beat 1 tablespoon butter at low speed of a mixer until creamy. Add remaining ingredients, beating just until blended. Spread over tops of loaves.