To make an easy creamy sauce you can use some milk and use a thickening agent such as flour even some cornstarch, which can give the sauce a rich and smooth texture.
A common method for creating a creamy sauce is to make a roux, by cooking some fat such as butter, bacon grease, sausage grease etc together in a pan and then slowly whisking in the milk to make a white sauce base, which can also be seasoned and enhanced using other ingredients.
To make a creamy sauce with milk, melt a small amount of butter or margarine or other fat like bacon grease, sausage grease etc in a saucepan over medium heat, then whisk in an equal amount of all purpose flour to the melted fat to form a paste, then cook this for a minute or two to get rid of the raw flour taste.
Then slowly add milk to the roux and whisk constantly to prevent lumps and ensure you get a smooth creamy sauce.
Then continue cooking and stir the sauce until it gets to the thickness that you desire.
And then add some salt, pepper or any other seasonings that you want, like nutmeg or other herbs.
If you want a richer creamy sauce you an also stir in a pat of butter at the end or even add some Parmesan cheese to add flavor to your creamy sauce.
To thicken milk, you can boil the milk on the stove which will evaporate the water and add a starch based thickener like flour or cornstarch to a cold slurry before you add it to heated milk.
You can also thicken milk by incorporating other dairy products into the milk such as cream cheese for making savory sauces or even some condensed milk for sweets.
You can also thicken milk by using other thickeners like tapioca starch, xanthan gum or gelatin, although these thickeners will require specific methods.
To thicken milk using starch based thickeners start by preparing a slurry.
In a small bowl, start by mixing a starch like tapioca starch, flour or cornstarch with a small amount of cold milk or water until it forms a smooth and lump free paste.
Then heat the remaining milk in a pot over low heat.
Next slowly whisk the starch slurry into the heated milk and then bring the mixture to a gentle simmer, while stirring the mixture constantly to prevent it from burning and prevent lumps, until the mixture reaches the thickness you desire.
To thicken milk by boiling, place the milk into a saucepan over low heat.
Then allow the liquid to evaporate slowly, which concentrates the milk and makes the milk thicker.
While simmering the milk over low heat, stir the milk constantly to prevent the milk from scorching on the bottom of the pan.