Add mushrooms, onion and garlic to a food processor. Process until chopped fine.

Place butter into a medium skillet. Place over medium heat.

When butter has melted and is hot (do not burn), add mushroom mixture. Cook thoroughly.

Sprinkle in flour. Continue cooking for a few minutes until well-incorporated.

Pour in brandy. Cook for 5 more minutes to enhance the depth of flavor.

Add cream and half & half. Cook, stirring, until mixture becomes bubbly and thick.

Season with nutmeg and fresh sage.

Serve immediately or store in a tightly sealed container, in the refrigerator, until ready to serve. Reheat before serving.