Start by melting the butter in a small saucepan on low heat. Cook until butter is melted and turns golden in color. Set aside.

In a medium sized saucepan, whisk together ¼ cup of the non-fat buttermilk, cornstarch, salt, and cayenne pepper until smooth and well combined.

Add in the rest of the buttermilk and liquid egg substitute.

Set the pan on medium-low heat, and whisk continuously until it begins to simmer and thicken.

Remove from heat and whisk in the lemon juice and butter.