1. Make the Crispy Topping: Preheat your oven to 350°F. On a lined baking sheet, toss the panko breadcrumbs, shredded cheddar cheese, and melted butter together. Spread them evenly and bake for 8 to 10 minutes until golden and crispy. Set aside to cool.

2. Sauté the Base: In a large skillet or a Dutch oven over medium heat, melt the unsalted butter. Add in the diced onion with a pinch of salt and cook for 4 to 5 minutes until the onions are softened and translucent.

3. Add Garlic and Broccoli: Stir in the minced garlic and cook for 1 minute until fragrant. Then, toss in the chopped broccoli florets and cook for 5 to 6 minutes until the broccoli is bright green and just tender.

4. Build the Sauce: Incorporate the flour and Dijon mustard, cooking for about a minute. Gradually whisk in the vegetable or chicken broth followed by the whole milk, whisking continuously to avoid lumps.

5. Simmer: Bring the mixture to a gentle simmer, stirring occasionally for about 5 to 7 minutes until the sauce thickens nicely.

6. Add Cheese and Beans: Remove the pan from heat, then stir in the freshly shredded cheddar cheese until fully melted and smooth. Fold in the seasoned butter beans, returning to low heat for 3 to 5 minutes until the beans are warmed through.

7. Season and Serve: Taste your creation and adjust salt and pepper as needed. Ladle the mixture into bowls and generously top with the crispy cheddar topping and a pinch of optional red chili flakes for added heat.