Preheat a large grill pan or griddle over medium heat. Butter one side of each slice of bread. When the griddle is hot, lay the bread slices buttered side up and toast until just lightly browned. Flip the slices so they're buttered side down. Immediately lay one slice of cheese on each slice of warmed bread. Let the bread grill while you work on the sausage. When the cheese begins to melt, turn down the heat to medium-low so that the bread doesn't burn.

Meanwhile, heat a small skillet over medium heat. Add the sausage and onions, and saute until the sausage is completely cooked through. Whisk the eggs, adding cream or milk (if using), then pour into the pan with the sausage. Turn heat to medium-low. Use a spatula to move the eggs around the pan, gently mixing in the sausage and onions while making sure the eggs are scrambling and not sticking to the pan. Season with a big pinch of salt and pepper.

Divide the eggs and sausage mix into 4 servings, and transfer each serving to a slice of bread. Top the eggs and sausage with a slice of bread (cheese side down) to create four sandwiches, and press gently with a spatula to help the melted cheese glue the sandwich together. Check the underside of the sandwich to make sure it's nicely golden and toasted.

Serve immediately. Try to restrain yourself from making more. Or don't. It's comfort food season, people.