Once the butter is melted, whisk in the starch until it's fully incorporated. Allow the roux to thicken.
Once the roux has started to thicken, slowly whisk in the milk or half and half. Do NOT overcook the sauce at this point. Remove it from the heat if it starts to thicken too much.
Remove the sauce from heat and stir in the spices and mix till combined.
Stir in the shredded cheese until it is fully melted and the cheese sauce is smooth.
Top your favorite veggies with the cheese sauce for a delicious side dish the whole family will devour.
Notes
Keep the temperatures lower - You might think going higher will make it come together fast, but it can cause the dairy to curdle and separate if you aren't careful.
Make sure the butter and starch are fulling combined and started to thicken before adding the milk. This will ensure a solid base for the sauce.
Once you add the milk or half and half, remove it from the heat, so it doesn't start to thicken more than you want it to, as it will make it hard to add the cheese. Don't worry if you want it thicker in the end; just place the sauce over medium-low heat and stir until it's thickened to desired consistency. A good rule of thumb is to see if the sauce just starts to coat the back of the spoon. If it does, take it off the heat.