Preheat your oven to 375°F (190°C) and lightly grease a 9x13-inch baking dish.

Heat olive oil in a large skillet over medium heat. Add the diced onion and cook for 5 minutes until soft and translucent.

Stir in the minced garlic and cook for an additional 1 minute until fragrant, then remove from heat.

In a separate medium saucepan, melt the 2 tablespoons of butter over medium heat. Whisk in the flour and cook for 1 minute to form a roux.

Gradually whisk in the warm milk and heavy cream, ensuring no lumps form, and simmer until the mixture thickens.

Reduce heat to low and stir in 1 cup of the cheddar cheese and all of the parmesan cheese until melted and smooth. Season with smoked paprika, salt, and black pepper.

In the prepared baking dish, combine the drained cannellini beans, black beans, and the cooked onion and garlic mixture.

Pour the creamy cheese sauce evenly over the bean mixture, stirring gently to combine everything.

In a small bowl, toss the panko breadcrumbs with the tablespoon of melted butter and the remaining 1/2 cup of cheddar cheese, then sprinkle evenly over the bake.

Bake uncovered for 25 to 30 minutes, or until the sauce is bubbly and the breadcrumbs are golden brown.

Garnish with freshly chopped parsley before serving warm.