Start by cutting a head of broccoli, removing the stem and cutting it into florets.
Transfer everything to a medium saucepan and add enough water to cover.
Put the lid on the pan, turn the heat to medium and let it all cook for 8 minutes.
After this time has passed, drain all the water and set aside.
In a large skillet over medium to low heat, add the unsalted butter and stir until completely melted.
Add the wheat flour and stir until a mixture forms.
Then, gradually add the milk at room temperature.
Keep stirring non-stop until a smooth and uniform creamy mixture forms.
Season with the salt, a pinch of black pepper, the garlic powder and stir until incorporated.
Add all the broccoli we prepared, the cheddar cheese and the grated mozzarella.
Cover the skillet and let everything cook until the cheese melts completely.
Serve.