Melt the butter in a small saucepan until it begins to foam. This allows the water in the butter to cook off which will create a smoother consistency.
Add the diced mushrooms and cook for 5-6 minutes, until liquid is mostly reduced.
Add the flour and cook for an additional 3 minutes, stirring occasionally.
Add the chicken broth and stir to combine. Slowly mix in the half and half until combined, then add the seasonings.
Whisk continuously and bring to a gentle boil. Stir continuously while it bubbles for about 4 minutes, it will thicken and reduce.
Remove from heat. It will continue to thicken upon standing.
