Preheat a grill to medium high. Combine the beer, apples, onion, 1/2 teaspoon salt and 1/4 teaspoon pepper in a saucepan and bring to a simmer over medium heat. Add the brats and simmer, stirring occasionally, until cooked through, 10 to 15 minutes. Strain the brats, reserving 1 cup of the poaching liquid. Brown the poached brats on the grill, turning, 5 to 6 minutes.
Make the beer-cheese sauce: Combine the Velveeta, 3/4 cup of the reserved poaching liquid, the pickled jalapenos and mustard in a small saucepan over low heat. Cook, stirring constantly, until melted and combined. Add more poaching liquid if you want to thin the sauce. Keep warm.
Sandwich build: Split the baguette in half lengthwise and lightly toast on the grill. Halve the brats lengthwise and layer them on the baguette bottom. Top with the sauerkraut, a drizzle of the beer-cheese sauce and the baguette top. Cut into individual sandwiches and serve with the remaining beer-cheese sauce.
Photograph by Kang Kim
Recipe courtesy Jeff Mauro for Food Network Magazine