Prepare the Rarebit Sauce:

1. In a medium saucepan, melt the butter over medium heat. Stir in the flour and cook for 1-2 minutes to form a roux.
2. Gradually whisk in the stout beer (or milk) and heavy cream, stirring constantly to avoid lumps. Cook until the mixture thickens slightly, about 2-3 minutes.
3. Reduce the heat to low and stir in the grated cheddar cheese, Dijon mustard, Worcestershire sauce, and paprika.
4. Continue stirring until the cheese melts and the mixture is smooth. Season with salt and black pepper to taste. Remove from heat and keep warm.

Toast the Soda Bread:

1. If desired, lightly butter the slices of soda bread. Toast them under a broiler or in a toaster oven until golden brown.

Assemble and Serve:

1. Place the toasted soda bread slices on a serving plate.
2. Generously spoon the warm rarebit sauce over each slice.
3. Sprinkle a pinch of paprika or chopped chives on top for garnish.
4. Serve immediately with a side of pickles, a green salad, or even a poached egg for added flair.