Preheat oven to 450°F.
Scrub potatoes and roughly chop, then toss in 1 Tbsp oil and season with salt and pepper. Bake potatoes on a sheet pan for 20 minutes.
Trim green beans, toss in 1 Tbsp oil and season with salt and pepper.
In a small bowl, combine the mayonnaise and hot pepper sauce. Set aside.
In another bowl, combine the breadcrumbs and butter. Set aside.
Remove potatoes from the oven; cut haddock into 4 pieces, season lightly with salt and add to the pan alongside potatoes. Brush fish with 1 Tbsp spicy mayo and cover with breadcrumbs.
Add green beans to tray.
Bake for 8 to 10 minutes or until the fish is fully cooked through and the breadcrumbs are lightly golden.
Serve the fish and vegetables with the remaining spicy mayo and enjoy!
