Heat about 1½ tablespoons olive oil in a frying pan over medium heat. Add the grated ginger and crushed garlic, stirring frequently. Cook for about two to three minutes until fragrant and slightly golden.
Sprinkle in the cumin seeds, curry powder, and chilli flakes. Stir them into the hot oil so the spices release their aroma. Cook for about 30 seconds to deepen the flavor before adding the beans.
Add the drained butter beans to the pan along with salt and black pepper. Stir everything together so the beans are coated in the spiced oil. Cook for a minute or two until the beans are heated through.
Turn off the heat and allow the mixture to cool slightly for a few minutes. Then stir in the double cream, grated cheddar, and chopped coriander. The cheese will begin to melt into the warm beans, creating a creamy sauce.
Place the slices of sourdough on a baking tray and grill them lightly until the first side becomes golden. Flip the bread over and drizzle a little olive oil on the untoasted side. This step ensures the toast stays crisp even after adding the topping.
Spread the cheesy bean mixture generously over each slice of toast. Place the tray back under the grill for four to five minutes. The cheese will melt fully and form a golden, bubbling layer on top.
Remove the toast from the grill and spoon some of the pickled onion mixture on top. The tangy onions cut through the richness of the beans and cheese. Serve immediately while everything is warm and creamy.