PREPARATION:

1. Heat water in small saucepan over low heat until temperature reaches 105° to 110°F. To proof yeast, sprinkle yeast and sugar over heated water in large bowl; stir until dissolved. Let stand 5 minutes or until mixture is bubbly. Add all-purpose flour, 2 tablespoons butter, eggs and salt. Beat with electric mixer at low speed until blended, scraping down side of bowl once. Increase speed to high; beat 10 minutes, scraping down side of bowl once. Stir in whole wheat flour until soft dough forms. Cover with plastic wrap; let rise in warm place 1 hour or until doubled in bulk.
2. Meanwhile, cook onion in remaining 2 tablespoons butter in small skillet over medium heat about 4 minutes or until tender. Remove from heat; cool.
3. Spray 9-inch pie plate with nonstick cooking spray. Sprinkle dough with cheese and half of onion, stir until evenly distributed. Turn into pie plate. Spoon remaining onion over dough; sprinkle with poppy seeds. Let rise in warm place, covered, about 1 hour or until doubled in bulk.
4. Preheat oven to 375°F. Uncover loaf. Bake 30 minutes or until loaf sounds hollow when tapped. Remove from pie plate. Cool on wire rack 30 minutes. Cut into 12 wedges before serving.