Step 1

Heat 2 Tbsp. oil in a large heavy pot over medium heat. Add onion and cook, stirring occasionally, until soft but not browned, 8–10 minutes. Add garlic and cook, stirring constantly, until fragrant, about 1 minute. Add butter and stir until melted. Add flour and cook, stirring constantly, until beginning to turn golden brown, about 4 minutes.

Step 2

Whisk in broth, beer, and cream. Bring to a boil, reduce heat, and simmer, whisking occasionally, until thickened, 10–15 minutes. Reduce heat to low and whisk in cheese a handful at a time, whisking to combine after each addition. Cover and let sit for 10 minutes to ensure cheese is melted. Working in batches if needed, transfer soup to a blender and purée until smooth (alternatively, use an immersion blender in the pot). Season with salt and pepper.

Step 3

Using a paring knife, score sausage, spacing cuts ½” apart. Heat 1 tsp. oil in a large grill pan or skillet over medium-high heat. Cook sausages, turning occasionally, until browned and crisp in spots, 8–10 minutes. Transfer to a plate.

Step 4

Toss apple in remaining 1 tsp. oil in a small bowl. Cook in same grill pan until softened and slightly charred on both sides, about 2 minutes per side.

Step 5

Divide soup among bowls; top with sausage and apple.