Begin by placing your bright green broccoli florets in a large saucepan, adding just enough water to cover the bottom. Bring the water to a simmer over medium-high heat, then cover the pan with a lid. Cook for about 4-5 minutes, until the broccoli turns a vibrant green and becomes crisp-tender.

Once the broccoli is ready, carefully drain it using a colander. Cover the florets with a kitchen towel to keep warm.

In the same saucepan, melt 2 tablespoons of butter over medium-low heat. Whisk in 2 tablespoons of flour until it forms a smooth roux.

Gradually pour in 1 cup of milk while whisking continuously. Cook for around 3 minutes until thickened.

Reduce the heat to low and add 1 cup of shredded cheddar cheese, stirring until melted.

Stir in ¼ cup of grated Parmesan cheese along with salt, ground mustard, and cayenne pepper if desired.

Gently fold the warm broccoli into the cheese sauce, or serve the sauce poured over the broccoli.