Be sure the oat mixture has cooled before mixing with the yeast.
Stir together first 3 ingredients in bowl of a heavy-duty electric stand mixer until butter melts. Stir in brown sugar and next 2 ingredients. Cool until lukewarm (20 to 30 minutes).
Meanwhile, stir together 1/2 cup warm water, yeast, and granulated sugar in a 1-cup glass measuring cup; let stand 5 minutes.
Stir together bread flour and next 3 ingredients in a medium bowl. Stir yeast mixture into oat mixture. Gradually add flour mixture to oat mixture, beating on low speed until well blended.
Sprinkle a flat surface generously with bread flour. Turn dough out, and knead until smooth and elastic (about 6 to 8 minutes), sprinkling surface with bread flour as needed. Place dough in a lightly greased large bowl, turning to grease top. Cover and let rise in a warm place (80° to 85°), about 1 hour or until doubled in bulk.
Punch dough down; turn out onto a lightly floured surface. Divide dough in half. Roll each half into an 18- x 9-inch rectangle. Starting at short end, tightly roll up each rectangle, jelly-roll fashion, pressing to seal edges as you roll. Pinch ends of dough to seal, and tuck ends under dough. Place each dough roll, seam side down, in a lightly greased 9- x 5-inch loaf pan. Cover and let rise in a warm place (80° to 85°) 1 hour or until doubled in bulk.
Preheat oven to 350°. Bake 30 to 35 minutes or until loaves are golden brown and sound hollow when tapped. Remove from pans to a wire rack, and brush loaves with melted butter. Cool completely (about 1 hour).