In a small pot, melt the butter and then add the flour.
Let cook for 1-2 minutes until nutty smells emerge and looks like wet sand.
Add the milk and bring to a simmer to thicken.
Turn down the heat to low and add the shredded cheese.
Once the cheese is incorporated, thin the sauce with the Corona and season with cayenne (optional), salt and pepper.
Cook broccoli and cauliflower until tender.
Carefully remove the vegetables from the steamer package and drizzle the warm cheese sauce.