Slow Cooker Salisbury Steak and Mashed Potatoes

INGREDIENTS

1/4 tsp

crushed black pepper, divided

8 oz

crimini mushrooms, sliced

2 tsp

Worcestershire sauce

parsley, for garnish (optional)

russet potatoes, scrubbed clean

4 tbsp

butter

1/2 cup

sour cream

1 cup

whole milk or heavy cream

1/2 tsp

Kosher salt

1/4 tsp

ground black pepper