| Dissolve yeast in 1/4 cup warm water; set aside. With metal blade in place, combine flour, sugar and salt in bowl; process 5 to 10 seconds to combine. Pour yeast mixture and warm milk through feed tube. Process 5 to 10 seconds to combine. Add 1 tablespoon butter. Begin processing; then slowly pour remaining water through feed tube just until ball forms, about 10 to 15 seconds (all water may not be needed). Continue processing for 60 seconds to knead dough.
Carefully remove dough and blade from processor bowl. Shape dough into ball and form hole in center. Stretch dough and fit back into processor bowl; grease top. Cover, let rise in warm, draft-free place until doubled in size, about 30 to 45 minutes.
Punch dough down. Remove dough to lightly floured surface; roll to 14- ? 8-inch rectangle.
Melt remaining 2 tablespoons butter; stir in onions. Evenly spread onion mixture over dough to within 1/2-inch of edges; sprinkle with pimientos and cheese. Beginning at long end, roll up tightly as for jelly roll. Pinch seam to seal. With sharp knife, cut roll into 12 equal pieces. Place pieces, cut sides up, in greased 8-inch round cake pan; cover. Place shallow pan on counter; half-fill with boiling water. Set wire rack over pan; place cake pan on rack. Let rolls rise 20 minutes.
Bake at 375?F for 25 to 30 minutes or until done. Remove from pan to wire rack. Serve warm.