Heat a large nonstick skillet over medium-high heat. Add onion to pan; sauté 5 minutes or until tender. Remove from heat.
Place onion in a 2 1/2-quart electric slow cooker coated with cooking spray. Add cheese and next 5 ingredients (through cream cheese). Stir until blended. Cover and cook on LOW for 1 1/2 hours or until cheese melts, stirring after 45 minutes. Top with green onions and bacon.
I fixed this for a wine-tasting party. I had three other hot dips. This was clearly the favorite - the slow cooker was entirely cleaned out. I followed the instructions pretty carefully. The bacon and green onions, I think, attracted attention just by their appealing aroma.