In a large pot of boiling salted water, blanch the cauliflower for 2 minutes and place in cold water. Set aside.
Add the Swiss chard to the water and blanch for 30 seconds; remove and place in a separate bowl of cold water. Set aside.
In a medium pot, heat the 4 tablespoons of unsalted butter. Once melted, add the flour and gently cook on medium heat for 30 seconds.
Using a whisk, add in the milk slowly, continuously whisking to avoid lumps.
Season with salt and pepper; add in 1 cup Black Diamond Reserve 1 Year Old Cheddar cheese. Stir until melted and combined, then add in the oregano and set aside.
Butter a 9-inch round baking dish or a 9×13-inch oven-safe dish.
Mix the cauliflower, Swiss chard, cheese sauce and cherry tomatoes in a bowl, then place in the Pyrex dish.
Melt the 1 tablespoon of unsalted butter; mix with panko and ½ cup of grated Black Diamond Reserve 1 Year Old Cheddar.
Sprinkle the panko mixture over the cauliflower mixture and bake in the oven at 375 F for 35 minutes until bubbly and golden brown.
For extra crunch, set the broiler on high and place your oven-safe dish back in the oven for 3-5 minutes. Pay close attention to not burn the topping.