In the bowl of your slow cooker, layer the onions, 3 tablespoons butter, and then the chicken. Sprinkle the chicken with thyme, sage, garlic, and season with salt and pepper. Pour over the wine and broth. Add the mushrooms. Cover and cook on low for 3-4 hours or on high for 1-2 hours.

Preheat the broiler to high. Remove the chicken and most of the onions from the slow cooker and place on a baking sheet.

Crank the heat on the slow cooker to high. Stir in the orzo and 1 cup water. Cover and cook 20-30 minutes, or until the orzo is al dente. If the orzo needs more liquid, add additional water. Stir in the cream and parmesan.

Arrange 3 tablespoons butter over the onions, top the pan with gruyere. Broil 3-5 minutes, until the cheese is melty.

Serve the chicken and onions over the orzo.