In a medium sized heavy sauce pan melt the butter. Once the butter is completely melted add the flour and Thick Gel and stir well to combine. Let cook for 30 seconds then whisk in the milk. It won't look thick enough, but it will thicken as the temperature increases. Cook for 3-4 minutes until thick and creamy. Add lemon juice, mustard and spices. Add extra milk if needed to maintain a pourable consistency.