In a large skillet, melt one tablespoon of unsalted butter over medium. Add one leek to the skillet and sprinkle with coarse salt. Cook until tender and slightly caramelized, about 12 minutes.
Transfer leek mixture to a large bowl and add 2 cups of shredded cheddar, 8 oz package of cream cheese, ¼ cup of mayonnaise, and 3 tablespoons of stout beer. Mix until smooth and well incorporated.
Transfer to a 1-quart baking dish and bake until bubbling and browned on top, 18 to 20 minutes. Serve on slices of baguette.
Notes
Stout Beer - I like to use a stout beer such as Guinness or even an Oatmeal Stout works well too.
Caremelizing - Be patient when caramelizing the leeks; low and slow cooking will develop their sweet flavor without burning them.
Cheese - Don't skimp on the cheese! Using high-quality cheddar cheese will elevate the taste of the dip.
Topping - To achieve a golden-brown crust on top, broil the dip for the last few minutes of baking, keeping a close eye to prevent burning.
Seasonings - For extra depth of flavor, consider adding a pinch of smoked paprika or cayenne pepper to the dip mixture.