Heat a saucepan. Keep the heat to a low and add the butter.When the butter melts and starts to bubble, then add 1 tablespoon whole wheat flour or 2 tablespoons all-purpose flour.

Using a wired whisk stir the flour quickly as soon as you add it. Keep on stirring so that no lumps are formed

The frequent stirring helps the flour to cook evenly. You will see the flour frothing and bubbling up while stirring.

Sauté the flour till you get a nice cooked aroma from the flour and a pale golden color. Don't brown the flou

Keep the heat to the lowest and then pour the cold or chilled milk in a gentle stream. Pour the milk with one hand and stir the sauce mixture with the other.

The milk has to be chilled, so that lumps are not formed. If you use hot or warm milk or milk at room temperature, lumps can be formed.

Do stir frequently while the milk warms and heats up.

On a low heat, simmer the sauce till it thickens.

When the sauce has thickened well and coats the back of a spoon, turn off the heat.

Keep the pan.Add butter, sliced onion and chopped garlic. Mix very well and set aside

Add cooked pasta in white sauce.Add sliced onion and garlic in it.Add ¼ teaspoon each of dried oregano, chilli flakes.