Cheesy Broccoli and Cauliflower Gratin

Firstly, preheat your oven to the desired temperature of 375 degrees F (or 190 degrees C). Next, take a small amount of butter and grease a suitable baking dish.

Cut the cauliflower into large florets, while cutting the broccoli into similar-sized pieces; peel and cut the broccoli stalks in quarters.

Submerge a large pot of water into boiling point; add cauliflower and cook until it reaches the desired level of tenderness but still retains its firmness, approximately 8 to 10 minutes. Transfer the cooked cauliflower into a strainer using a spoon with holes; rinse under cold water to stop cooking. Add broccoli stalks to the pot and cook for 3 minutes; add broccoli florets to the pot and continue cooking until both stalks and florets are tender but still firm, roughly 5 minutes more. Transfer the cooked broccoli into a strainer and rinse under cold water to stop cooking. Finally, dry both cauliflower and broccoli with paper towels before placing them in the prepared baking dish.

Melt 1/2 cup of butter in a saucepan over medium heat; whisk in flour to create a thick paste. Continue stirring constantly until the flour begins to brown, approximately 4 minutes. Add milk and bring the mixture to a boil, stirring constantly until it thickens, 2 to 4 minutes more. Remove the sauce from heat; whisk in mustard, Worcestershire sauce, and pepper. Whisk in Cheddar cheese until it's fully melted and incorporated into the sauce. Pour the cheese sauce over cauliflower and broccoli; gently shake the baking dish on a flat surface to remove any air bubbles.

Mix bread crumbs and olive oil together in a small bowl; top the vegetable and sauce mixture with the bread crumb mixture. Finally, sprinkle paprika over the bread crumb mixture.

Bake in the preheated oven until it reaches a bubbly and golden brown state, approximately 30 minutes.